United face Barcelona tomorrow night in the Champions League semifinal and Fletcher said: "The most important thing is to pick ourselves up. We've got some big games coming up now.
"We've got to use this anger and we've got to fuel it in the right direction and focus on Barcelona and then those two league games.
"We did have some chances but unfortunately it did not just happen for us.
"As time goes on, naturally you start to drop back a little bit because you've got the point, which is a good result for you.
"But in the end they have got the penalty and won the game."
Fletcher was pleased with the way his knee stood up in the face of a physical battle.
He said: "I feel good. I was worn out a little bit in the last couple of minutes but that is natural.
"The knee is still a little bit painful but it's at a bearable level now so I can play."