Their midfield is shit without a performing Iniesta.
Only problem is Iniesta always performs in big games
Park the bus and allow iniesta time on the ball, and he will find new and exciting ways to get that front 3 through the defence.
However, play a very hard physical game against the cm's, and have your wingers commit consistantly in going down the flank at any given opportunity, and Iniesta will struggle, meaning barcelona will struggle. Just make sure they cant counter through the center.
PSG's first game was textbook. Hard physical midfield play and a genious deep playmaker able to pass in the space between defence and midfield with no time at all, having the CF stretch the defensive line and the wingers go down the flanks.
In fact, having Dybala operate behind that midfield, would be key.
Just dont park the fucking buss