Barca and Bayern are the only two previous winners still left in the competition but they go into the game in contrasting form.
Bayern have won 26 of their last 27 competitive matches, drawing the other, and have already secured a domestic double. Barca, meanwhile, are staring down the barrel of a first trophy-less season since 2007-08 after missing out on the La Liga title to Real Madrid.
The difference in form led Bayern legend Lothar Matthaus to claim the Germans would only fail to reach the semifinal if they make huge mistakes, while similar comments from people associated with the club have caused a furor in the Catalan press.
"I've heard [what's been said]," Vidal said in a news conference on Thursday when asked what he thought about the noise coming from the Bayern camp. "But I have not paid much attention to it.
"I know Bayern's players and what's said has come from outside and is not what [the players] think. They have a lot of confidence but they're not playing against a Bundesliga team on Friday, they're up against Barcelona, the best team in the world."
Vidal played 123 games with Bayern Munich from 2015-2018 and won three Bundesliga titles, two SuperCups, and the DFB Pokal in that span.
Three draws and a penultimate defeat against Osasuna in the league saw Barca give up a two-point lead over Real Madrid as they chucked away the title, raising doubts about Vidal's claim.
"I understand the criticism," the former Bayern midfielder added. "But we are the best team in the world. That wasn't reflected on the pitch in La Liga and we missed out on the title, but if we connect we can beat anyone. That is why I say we are the best and we have to show it against Bayern."
Lewandowski has scored 54 goals in all competitions this season and Matthaus has labelled him "better than Messi," a comparison that Vidal cannot get on board with.
"Lewandowski is extraordinary, tireless, a goalscorer, really dangerous," Vidal said. "I played with him for three years and saw him grow, saw how he trained, how he prepares.
"But it's very difficult to compare him with Leo, Leo's from another planet. Lewandowski is the best striker in the world, along with Luis Suarez, but you can't [compare with Messi]."
Bayern coach Hansi Flick seemed to echo Vidal's stance that there was only one Messi in his prematch press conference on Thursday.
"You can't compare them. Robert Lewandowski is an absolute world class player in attack," Flick said. "He's got huge qualities in the box. Someone who scores goals and sets up goals. Messi is one of a kind. It's not even sure there will ever be a player like him again."
As for how the team will defend the Barca talisman, forward Thomas Muller said that it would take a team effort to try and stop him.
"You can't defend [Messi] alone," Muller said. "My experience has shown that it only works if the entire team is there. When the first player does not win the ball, the next one is there and if he's also not winning the ball, the first player must show up again and steal it. It's not just [Alphonso] Davies. It's about going into the duels, being aggressive but fair.
"We can only defend the individual quality, not only Messi's, as a team."
Unsurprisingly, Barca coach Quique Setien also took up Messi's side of the debate.
"It's true Lewandowski is a great player, but I don't think he's at Leo's level, I think that's clear," Setien said. "He's in a great moment of form -- I think 13 goals in the Champions League -- but so is Leo. We saw that against Napoli."