I wouldn't say Barcelona got lucky, it would be more correct to say that Flick finally outplayed Simeone. Last match Barcelona led 4:2 and on 83 minutes Flick put away Rafinha and Pedri and after that Atletico scored 2 more goals and equalized. This time Flick left Rafinha until the end and it was him who made the goal on 98 minutes for Ferran Torres, and Ferran Torres was released by Flick instead of Olmo and this substitution worked, because Ferran Torres scored 2 goals. Lewandowski scored a great first goal that helped Barca and the decision not to change him, despite not a good first half, also worked. Flick proved to everyone that he is truly a top coach and now Barcelona are fighting not only to win La Liga, but also to win the Champions League.
Simeone still great coach, because he is squeezing the maximum out of the squad he has and if not for the excellent transfer of Julian Alvarez, Atletico would be even harder to fight in Lal liga and in Champions league.
Hansi Flick has turned and rebranded Barcelona to a beast. I would say they're in a beast mood as it stands. After Atletico Madrid went 2 - 0 up I thought it was over, worse case scenario would be 2 - 2 but that coach has something else up his sleeves because he wouldn't fall twice to Atletico Madrid in the same competition this season, lol. Seriously this Barcelona team is something else, their mood and manner of approach to games this second half of the season is actually top notch.