I'm not at all sure that in terms of players, Barcelona will be ahead, but it doesn't matter - football is a team game and United look much stronger here. United are more flexible and they are able to play with different opponents using different strategies. I don't follow Barcelona much but their game looks like either stupid ball rolling or crosses on Lewandowski "for good luck" with extremely low efficiency. Is there any chance Xavi will come up with something new? I highly doubt it.
Right now, we are nearly forty days away from this game which is clearly good length and during this time anything can happen which can bring trouble for any team with any team can go much better but in current situation performance and quality is clearly supporting Manchester United which is doing good performance after the International break and having three good wins with clean sheets .
Moreover, Barcelona is having one derby match which was ended in a draw so if Barcelona wants to win against Manchester United then surely they need to improve their performance and having better depth in squad will help them in Manchester United now things looking better which are helping them for having improved results and better quality.