The Red Bull hype was real. Preaseason suggested Mercedes' domination of F1 was under threat after seven years at the top and that was confirmed by Max Verstappen's late lap in qualifying for the Bahrain Grand Prix.
Verstappen will line up alongside reigning seven-time world champion Lewis Hamilton at Sunday's race.
That's a sight Formula One fans might quickly get used to in 2021.
How did Verstappen beat Hamilton?
After two weeks of speculation, we finally have confirmation that Max Verstappen has a car capable of taking the fight to Mercedes at the opening race of the season.
A combination of a brilliant lap by the Red Bull driver and ongoing struggles for the Mercedes drivers was enough to open up a 0.388s gap between Verstappen and Lewis Hamilton on Sunday's grid.
But just as we were cautious about backing Red Bull after testing, we have to remind ourseleves not to hand Verstappen the championship after a single qualifying session.
The size of Verstappen's advantage over Hamilton was undoubtedly impressive relative to last year, but the combination of preseason testing, Friday practice and Saturday's qualifying only offers a snapshot of the cars' potential, and crucially, only applies to a single circuit.
The Bahrain International Circuit has two main characteristics: It's power sensitive, benefitting the best engines on the grid, and it chews up rear tyres, benefitting a well-balanced car.
By coincidence, it seems those are the two areas where Red Bull has made the most ground over the winter and, potentially, the two areas of Mercedes' weakness this year.
"I think the car is just not in a happy place, and Bahrain wasn't particularly great last year either," team boss Toto Wolff said on Saturday evening. "This is a track layout and asphalt that Red Bull seems to master better than us.
"But this is not at all an explanation that is acceptable. We just need to do what we've done in the last year and understand the car and the tyres, and then we will be back in the fight."
Sunday's race could still be a different story, with Verstappen and Hamilton looking very closely matched on heavy fuel during race simulations in Friday practice.
However, Mercedes appeared to struggle more with rear tyre degradation, losing an average of 0.3s per lap over the first eight laps of a stint, and that could be the difference in allowing Verstappen to disappear into the desert if he gets a clean start and leads the pack at the end of lap one.
Why are Mercedes struggling?
After seven successive Mercedes title victories, it's a surprise to see Red Bull start the season as the team to beat.
But dig a bit deeper into why Mercedes is struggling and most lines of inquiry lead to changes made to the aerodynamic regulations over the winter.
On the face of it, the cars look very similar to their 2020 equivalents, and that's largely down to cost-saving measures that required the majority of the 2020 designs be carried over to 2021.
In theory, that should have benefitted Mercedes by freezing the competitive order, but the cost saving measures were combined with tweaks in the aerodynamic regulations aimed at reducing downforce.
That reduction of downforce was necessary to curb cornering speeds, which were starting to put dangerous levels of stress through the tyres, risking failures.
After three tyre failures at last year's British Grand Prix, the feeling was that aerodynamic development had to be curbed to prevent a serious safety issue arising over the course of 2021.
But it seems the changes to the aerodynamic regulations, which focused on the floor of the car, the rear brake ducts and the diffuser, impacted the performance of some teams more than other.
Based on comparisons between last year's qualifying times in Bahrain and this year's, Mercedes has lost two seconds of performance while Red Bull has only lost 1.4s.
That could be attributed to Red Bull doing a better job, but the trend extends to the cars that have close links to the top two teams and therefore follow similar design philosophies.
Since the introduction of the existing generation of wide-bodied cars in 2017, Mercedes and Red Bull have been split in their aerodynamic thinking and the rest of the grid have filtered their own designs along similar lines.
Red Bull's approach, which is the most popular, requires the car to run with a high rear ride height relative to the front (known as a high-rake setup), while Mercedes' approach, which has won the last seven world championships, requires a relatively low rear ride height (known as a low-rake setup).
The only other team with a similar aerodynamic philosophy to Mercedes is Aston Martin (formerly Racing Point), and it too has lost over two seconds of performance compared to its 2020 lap times.
Meanwhile, Red Bull's junior team Alpha Tauri, which has as extreme a high-rake philosophy as Red Bull, has only lost 1.4s.
Again, we only have data from one competitive session to analyse, but for some people in the paddock the trend of low-rake cars losing more performance than high-rake cars under the new rules is no coincidence.
"I mean it's no secret that the changes ... of course they've been done to peg us back," Hamilton said on Saturday evening. "We had the changes last season to our engine [referring to the ban on qualifying engine modes] to do the same thing.
"But that's OK, we love a challenge and we don't look down on these things. We just work hard to do the best we can, and that's what we'll do."
Wolff added: "I'm not sure if the answer is so simple [as high- and low-rake cars being impacted by different amounts], but definitely there is a pattern that you just described. Low-rake cars seem to have lost more than the high-rake cars, but that is the situation.
"If we would say, well, we were just penalised by the regulations, that's it, we wouldn't be racers and we wouldn't be fighters. We just need to get the car back in its sweet spot so it can combat with our competitors."
More data -- including a race around the Bahrain International Circuit on Sunday evening -- will help confirm or deny the suspicions, but either way Mercedes is in a real fight to stay in touch with Red Bull this year.
Look who's back...
It's almost like he never went away. Almost.
Fernando Alonso returned to the cockpit of a Formula One car for a competitive session for the first time in two years and he didn't disappoint.
He will line up ninth on Sunday's grid in a car that often looked like it wouldn't trouble the top 14 during practice.
Yet he insists he is still getting up to speed after his time away from the grid.
"I have to get better myself first of all because even today it was the very first time on these grippy tyres to extract the maximum from the car," he said.
"I will need a couple of races probably to get up to speed, even the same tomorrow it will be the first time formation lap, the start lights, the first corner action -- it's simple things for a racing driver but after two years it's going to feel again like new.
"To do a pit stop under two seconds, all these things I will have to live it for the very first time again, and that's something I will need a couple of races to get up to speed, so let's see."
The Alpine doesn't yet look like a front runner, but that didn't stop Alonso from finding the upper echelons of its potential at the very first opportunity.
New team, same old Vettel?
Sebastian Vettel's performance was the big shock of qualifying. The four-time world champion was eliminated in the opening session, qualifying 18th out of 20 drivers.
Vettel's struggles at Ferrari were well documented, but this outcome is perhaps slightly misleading on paper compared to some of his performances in red over the past few seasons. Vettel was a victim of circumstances to some degree, with a poorly timed yellow flag effectively ruining his last Q1 lap, but the counter argument is that he should have never been in such a precarious position in the first place.
When told during his TV interviews he looked fairly relaxed considering his qualifying position, he replied: "If I panicked now would it help? If I was really upset?
"For sure I am upset and angry that it wasn't our fault in a way not to make it through, but yeah, we have to take it and do what we can, preparing tomorrow."
Vettel said he still has to get to grips with his new car.
"I'm learning. I think the quali was good and it felt positive. Obviously I only got like a lap and a half, but I think we still have a lot of work ahead of us and I think you know we would have hoped for a better start, but it is what it is.
"Hopefully tomorrow we have a good race. I think we can come up quite a bit and see what today brings."
Aston Martin teammate Lance Stroll gave a glimpse at the potential of the car by qualifying for Q3. He will start from 10th on the grid.
Gasly shines, Perez stumbles
The pace of Alpha Tauri was a big question-mark coming out of preseason -- the Faenza team seemed to place anywhere between third and seventh in preseason analysis pieces.
Yuki Tsunoda turned in a stunning lap in Q1 to go second but it was Pierre Gasly who stepped up in the next two sessions. There's plenty of hype around Tsunoda but the Japanese driver showed the kind of inexperience you might expect from someone making their F1 debut, dropping out of Q2 while Gasly showed the true pace of the car.
Anyone who has been following F1 recently will not have been surprised at Gasly turning in an impressive display, given his performances over the past year and a half since being demoted from Red Bull back to the junior team mid-way through 2019. His performance was even more impressive when compared to the new Red Bull man Sergio Perez, who was eliminated from Q2.
Perez's signing was to replace the out of form Alex Albon this year but also was a reflection on the lack of faith Red Bull has in Gasly after his failed stint with the team in 2019. That mindset has always been hard to understand given Gasly's recent form. The French driver's story since is well-known, having won last year's Italian Grand Prix for the junior team, and the comparisons with Perez are likely to be a feature of the 2021 season.
Gasly's future might not be with the Red Bull team but there will be plenty of suitors interested in his services for 2022 if Saturday evening's performance was anything to go by.
Perez takes the blame
There are no doubts about how good Perez is but he made a costly mistake with his first run in Q2, exceeding track limits and having his initial lap time deleted from the board. That time would not have been enough to advance to Q3 as it turned out, but it would have only increased the pressure on Perez to get the second one right.
Strangely, Perez and Red Bull decided to go back out on the medium tyre rather than play it safe and go out on the soft tyre. Doing so would have meant Perez started on the less desirable tyre tomorrow but would have likely resulted in easy passage through to Q3.
The medium-tyre lap was not good enough to advance.
Perez made no excuses for his performance and said his mistake robbed him the valuable experience of progressing to Q3, which he feels is vital for learning a new car quickly.
"I think I really need to go to different conditions," Perez said after qualifying. "I'm so disappointed I missed going into Q3 because that would have made a good difference in understanding two sets of tyres as a reference with Max in similar conditions. But unfortunately I didn't do the lap I should have done. Learning more about the car will just help me."
He added: "I just have to be patient with myself and it should be a matter of time."
Nikita Mazepin seems to have already earned himself a nickname on social media.
Haas' rookie spun twice in Q1, something he also did during Friday practice. The second spin happened as several drivers behind him were beginning crucial timed laps.
He will start his Formula One debut from 20th, barring any penalties for drivers ahead.
Mazepin said the spins were caused by his struggles to get to grips with the brakes.
"I had an issue with brake-by-wire," he said. "I locked up on the rears, I'm not sure why, at Turn 1," he explained. "The pedal just went long. We need to look into that. Something that I didn't really expect and shouldn't happen. I've never had it driving in the test before or free practice. Hopefully that won't happen tomorrow."