United don't have to compete with Barcelona in midfield (although they can). They can play indoor football by playing on the counterattack. Barcelona in this case will make 1000 passes in the center of the field and 100 stupid hinged pass to Lewandowski. Will it bring them success? Hardly. But United's counterattacks, I'm sure will turn into a few goals. But I'm not sure that the game will go according to this scenario, maybe Ten Hag will decide to play pressure and play the first number.
If you really believe that is how the game will go then I guess you haven't been watching this Barcelona. Barcelona have conceded just 4 goals from counter attack this season and have conceded 7 goals in the league. The last goal they conceded came against Betis and it was an own goal. The defense is the best and most inform part of Barcelona this season. Injuries made them concede that much against Bayern.
The game against United is going to be very tactical and if United want to depend on counter then they'll lose.