2-0 away from home means that Manchester United have the tie more or less wrapped up, so the only thing that will worry them would be if Schalke somehow fluke a goal between now and the end of the match, and even 2-1 would be a great result as far as Sir Alex Ferguson's side are concerned. So, they're playing a little bit of keep-ball, frustrating the hosts, who look like a beaten team.
If Schalke want to get back into this semifinal, they're going to have to do it very fast, because it doesn't look as though it's going to happen unless they get a miracle in the final few minutes of the game. Then again, they did beat Inter Milan 5-2 at the San Siro, after which a 2-0 home loss would ahve been fine, but expecting lightning to strike twice in the same place might seem a touch foolish. You'd be crazy to bet against Manchester United making the Champions League final now.