In fact, Barcelona isn't strong enough to beat Bayern. They are defeated with 2 goals, without scoring any goal (Bayern 2 - 0 Barcelona).
Barcelona may be stronger right now, but they still don't have the mentality to beat a big team like Bayern Munich. Especially, since Lewandowski is a Bayern former player, Bayern players know well how to stop Lewandowski from scoring. Look at the result today, Lewandowski can't score a single goal. Another factor is that Xavi looks not choose the right players for the midfield line. I'm surprised Xavi didn't put Frenkie de jong and Kessie as the starters. Barcelona has many rosters, but they don't know which ones are best to be the starters.
In the end Frenkie de Jong came on in the 61st minute of the second half, followed by Kessie in the 80th replace Busquets. With time remaining, Barcelona is still not able to repay Bayern's advantage
I conclude Barcelona are strong enough but they are not confident enough to be on the same pitch as Bayern especially with the hope of winning, Bayern is not the same as some of the clubs that Barcelona have met before. So Xavi needs to give something more for his club, because their journey in the Champions League this season will certainly not be easy