I don't sure with Primer League higher level than La Liga will make Barcelona loss compete against Manchester United at playoff round, seem Barcelona more favorite lead to next round than Manchester United based on domestic league achievement by both teams.
MU is not so bad, but I think Barcelona does have a chance to win the game. Even at the European level, it seems that the strategy implemented by Xavi still cannot work over to the European League, seeing that MU is currently in a not good mental condition. Indeed, there is still time for MU to improve their performance and strategy, but in otherside Barce will also improving their performance within this 2 weeks. I think barcelona can manage 1 goal to get 3 points.