If we learned one lesson from testing in Bahrain, it's that three days is not long enough to get a proper reading of the competitive order. But, as is the tradition at this time of the year, it hasn't stopped us trying.
Trends started to develop over the three days in Bahrain and by extrapolating those, digging into the lap times set by all ten teams and using an element of guesswork, we have come up with the following ranking of the teams ahead of the first race.
As we know from previous years, things change between testing and the first race, and the ranking below is based purely on what we saw in Bahrain rather than what might happen when the cars hit the track in the opening qualifying session...
The top two ... but not as you know them
1. Red Bull
Fastest lap: 1:28.960s (Max Verstappen, day three, C4 tyre)
Lap count: 369
After several seasons of slow starts, Red Bull is finally entering the 2021 season as the favourite for victory at the first race. The team won't admit to that and it may be difficult to accept after seven years of Mercedes dominance, but on the evidence of the Bahrain test Red Bull is on top.
Does that mean Mercedes' dominance has come to an end and we are crowning Red Bull as world champions? No. But it does mean Red Bull has produced a genuinely competitive car that should be able to challenge for race wins far more regularly this year.
Gone is the snappy, unpredictable nature of last year's RB16, replaced by a car that looks stable, responsive and, above all, fast.
Max Verstappen's fastest lap time -- set in the final hour of testing when track conditions were at their best -- gave a glimpse of what the Red Bull is capable of, while hinting that plenty had been left in reserve.
Red Bull opted not to put Verstappen on track on the fastest tyre compound, which would have provided another 0.3s in performance, and his top speed through the speed trap indicated his Honda engine was not in as high a setting as the AlphaTauri of Yuki Tsunoda in second place.
Verstappen's fastest lap of the test was backed up by an impressive race simulation with Sergio Perez at the wheel on day two. It compared favourably with the handful of other teams that completed a race sim over the three days, despite being completed in less favourable conditions.
Fastest lap: 1:30.025 (Lewis Hamilton, day three, C5)
Lap count: 304
While it's way too early to write Mercedes' chances of victory off at next weekend's Bahrain Grand Prix, the team is undoubtedly starting the season on the back foot. The W12 was difficult to drive during testing, with both drivers complaining of a lack of stability at the rear of the car and an overall lack of performance.
As of Sunday evening, the team did not know why.
The drivers' complaints manifested in slow lap times, with Hamilton's best attempt on Sunday evening a full second off Verstappen's fastest lap despite Hamilton using a softer compound tyre. History tells us that Mercedes runs heavier fuel loads than Red Bull during preseason testing, but it would have to be by a significant margin to make up the difference in lap time.
Based purely on what we could see -- and making allowances for tyre compounds and likely fuel loads -- the single-lap performance of the Mercedes in Bahrain was behind not just Red Bull but also Ferrari, McLaren and AlphaTauri. However, on longer runs, over which the team said the issue was less obvious, the W12's performance was raised clear of the midfield runners.
The two big questions ahead of the first race are: Can Mercedes resolve the car's handling issue? And, if so, how much performance would it unlock?
The engineering team back at base in Brackley are among the best problem solvers on the grid, so it's hard to imagine a solution won't be found at some point early in the season. But even if a fix is brought to the car in time for the first race, it's also hard to imagine Mercedes holding the same kind of advantage over Red Bull that it enjoyed at the start of the 2020 season.
Added to the handling issue was a gearbox problem on the opening day of testing, which cost the team a morning of track time and left it at the bottom of the overall lap count by the end of the test. The lack of mileage was surprising, but the team's main concern on Sunday evening was its lack of performance.
An even tighter midfield pack
Fastest lap: 1:29.611 (Carlos Sainz, day three, C4s)
Lap count: 404
Ferrari has made good progress over the winter, but don't be fooled, it is still a midfield team. Its position in this ranking is based on some impressive single lap runs on the final day, which provided a useful reference to compare with other teams but also left a margin for error that could see Ferrari drop down the order at the first race.
But here's the good news: Ferrari's new engine for 2021 appears to have provided the boost in performance the team needed. This is a crucial development for Maranello, as last year's car was designed around a horsepower number that was slashed in the fallout of an FIA investigation into Ferrari's 2019-spec power unit. The reduction in engine performance for 2020 meant the car was not only down on power but also had an inefficient aero package optimised around the previous year's horsepower figures.
Cost-saving regulations last year prevented Ferrari from bringing an engine update during the season, but it worked hard behind the scenes in 2020 and the fruits of its labour have provided a significant step in performance for 2021. That progress not only manifested in an impressive lap time set by Carlos Sainz on the final day, it was also evident in the car's speed trap figures.
Last year, Ferrari languished at the bottom of the top speed rankings, but in testing all the Ferrari powered cars looked more competitive and Charles Leclerc was second only to Yuki Tsunoda in the AlphaTauri (more on why Tsunoda's data is unreliable below). All promising signs, especially on a circuit that is notoriously power sensitive.
Combined with Sainz's hot lap on the C4 tyre compound on Sunday evening and a promising race simulation earlier in the day that placed the SF21 comfortably ahead of AlphaTauri and Alfa Romeo, Ferrari looks like it has returned to more familiar territory near the top of the midfield.
Fastest lap: 1:30.144 (Daniel Ricciardo, day three, C4s)
Lap count: 327
Considering it switched engine supplier from Renault to Mercedes over the winter, McLaren made a remarkably smooth start to the season. The car ran reliably over all three days of the test and appeared to have a decent level of performance.
The MCL35M turned heads on the opening day of testing when rivals spotted McLaren's novel approach to F1's new aero regulations regarding the diffuser. The rule change calls for a reduction in the length of strakes in the centre section of the diffuser, but McLaren's interpretation allows for two of the strakes to be angled so that they retain some of their length further back while sitting within the dimensions written down in rule book.
While the McLaren diffuser is not a silver bullet for performance, it will offer a benefit and technical director James Key was pleasantly surprised to learn his team was the only one to read the regulations in that way.
Frustratingly for our pace analysis, McLaren opted not to chase performance in the final 90 minutes of the test when the likes of Red Bull, Mercedes, Ferrari, Alpha Tauri and Alfa Romeo were on low fuel setting quick laps. Instead, new signing Daniel Ricciardo hit the track on heavy fuel to complete a race simulation that looked very promising but was caveated by the improved track conditions experienced once the sun goes down.
Alpine followed a similar run plan on the final day of the test and Riccardo appeared to hold a 0.2-0.3s advantage over Fernando Alonso's efforts on both performance runs and heavy-fuel runs. Such margins appear to be the difference between being at the front of the midfield and the rear this season, so McLaren's position, like all teams in the midfield, is far from secure heading to the first race.
5. Aston Martin
Fastest lap: 1:30.456 (Lance Stroll, day two, C5)
Lap count: 314
Due to a lack of mileage and a slightly different approach to testing compared to its rivals, Aston Martin was incredibly hard to place in this order.
A turbo issue on Sunday afternoon meant Sebastian Vettel did not get the chance to sample the AMR21 on qualifying-style runs and a gearbox problem on the morning of day two also limited his running. Lance Stroll set the team's fastest lap time at the end of the second day of the test, but drawing comparisons with the times set on the final day is difficult due to differing track conditions.
Vettel's long runs on heavy fuel on Sunday afternoon offered no clear indication that the car was the class of the midfield as the pink predecessor had been in 2020, but without knowing fuel loads it was all guesswork.
As a result, Aston Martin sits firmly in the middle of this ranking, with strong arguments that it could be placed higher but enough concerns over reliability and a lack of mileage that it could fall lower when racing gets underway.
Fastest lap: 1:29.053 (Yuki Tsnoda, day three, C5s)
Lap count: 422
On the face of it, AlphaTauri emerged as the star performer of preseason testing, but dig deeper and its performance came loaded with caveats.
Rookie Yuki Tsunoda lit up the timing screens on Sunday evening with a series of fast laps on soft tyre compounds to finish the test just 0.093s shy of Verstappen. But while the car is quick and should feature in the top ten more regularly this season, it's clear it's still firmly placed in the midfield.
On his fastest laps, Tsunoda was activating his Drag Reduction System outside the zones where it would be permitted on a race weekend and the speed trap figures suggest that gave him a massive top speed advantage at the end of the pit straight (13km/h faster than Verstappen using the same Honda engine).
In testing there are no rules governing where the DRS can be used, but it's indicative of the team looking to build up Tsunoda's confidence with some quick times on low fuel rather than pegging itself in a straight fight against the competition. It's also likely Tsunoda's top speed discrepancy was aided by the use of some of Honda's more potent engine modes, although that could be true of any driver setting a quick lap.
Regardless of exactly what was going on during Tsunoda's fastest laps, the AT02 still looks like a fundamentally fast car. It was well balanced in all types of corners, giving Tsunoda the confidence he needed to push hard and chase impressive lap times.
Earlier in the day, the Japanese driver also completed a race sim, which offered a fairly direct comparison with race sims from Ferrari and Alfa Romeo. Based on average lap times, AlphaTauri finished the imaginary Bahrain Grand Prix seven seconds behind Ferrari and three seconds clear of the Alfa Romeo, underlining how competitive the midfield is this season.
It's likely Tsunoda's more experienced teammate Pierre Gasly would have reduced the average lap time had he been at the wheel during the race simulation, so it's very possible the car will move up this ranking in his hands at the real-life Bahrain Grand Prix next weekend.
Fastest lap: 1:30.318 (Fernando Alonso, day three, C4s)
Lap count: 396
Like McLaren, Alpine ran out of sync with the majority of teams on the final day of testing and opted to send Fernando Alonso out on heavy fuel when track conditions were at their best. As a result, it's hard to read too much into the times, but a comparison with McLaren put Alonso 0.2 to 0.3s per lap off the pace of Ricciardo.
The fact we have placed two teams in the small gap between McLaren and Alpine shows just how close the midfield appears to be this year, but is also based on a lack of clear indicators that the Alpine deserves to be higher. That doesn't mean the A521 isn't capable of a top ten finish or a Q3 appearance at the first race, quite the opposite, but the supporting evidence from the three days of testing simply wasn't there.
On the plus side, the car was reliable over the three days and is definitely in touch with the other midfield teams. Combine those traits with Fernando Alonso's tenacity behind the wheel and it's not hard to imagine Alpine scoring some strong results this year.
8. Alfa Romeo
Fastest lap: 1:29.766 (Kimi Raikkonen, day three, C5s)
Lap count: 422
Alfa Romeo has a habit of featuring near the top of the timesheets in testing only to drop back down the order in actual competition. While the same will almost certainly be true this year, there is hope that Alfa Romeo has made progress over the winter and will be able to challenge for top ten finishes on a more regular basis.
A large part of that hope is pinned on the Ferrari power unit in the back of the C41, which appeared to provide a step in performance for both Alfa Romeo and the works Ferrari team. Straight-line speed is no longer the weakness it once was (Alfa Romeo was joint third fastest with fellow Ferrari customer Haas on Sunday) and Raikkonen's best effort in the final hour of testing was good enough to finish fourth fastest overall.
A race simulation on Sunday afternoon suggested Alfa Romeo should be able to mix it with AlphaTauri over a grand prix distance, and that would represent a positive step compared to 2020.
Fastest lap: 1:30.117 (George Russell, day three, C5)
Lap count: 373
Williams also showed a turn of pace in the final two hours of testing on Sunday, with George Russell finishing the test sixth fastest and just 0.092s off Lewis Hamilton on the same tyre compound. A difference in fuel load is the most likely explanation for the surprisingly small gap, but it underlined the progress made by Williams, not to mention the lack of performance from Mercedes.
Russell said the FW43B was a clear step forward compared to last year, but admitted the car's aerodynamic performance was incredibly sensitive compared to previous years. That created some issues for test driver Roy Nissany and race driver Nicholas Latifi during high winds on the first two days of testing, but Russell said the pursuit of peaky performance was a conscious decision by the team in the belief it will elevate the car into points positions at certain circuits this year.
Whether it will hamper Russell and Latifi when running in traffic remains to be seen, but there are at least some signs that Williams will occasionally be a part of the midfield fight rather than struggling alone at the rear.
Fastest lap: 1:31.531 (Nikita Mazepin, day three, C4s)
Lap count: 394
A decision not to bring any major updates to its car over the winter means it is no surprise to see Haas at the back of the pack this year.
The car has been altered to meet 2021's new aero rules, but very little else has been developed and the team's resources have been diverted to preparing Haas for the upcoming overhaul of technical regulations in 2022.
For 2021, it will likely leave Mick Schumacher and Nikita Mazepin with a car that is multiple tenths off the pace of the Williams and firmly at the back of the grid. That's a shame for the two rookies, but Haas has always been clear that 2021 would be a year of transition.