Rio Ferdinand admits United's players have been hurting this week after the 2-1 defeat to Manchester City, and says the only way to get it out of their system is to beat Arsenal on Saturday.
The most disappointing aspect of the defeat for the 29-year-old was the Reds' failure to show any of the characteristics that have placed United among three title challengers this season.
"We didn't do any of the things that have taken us into a good position in the league and made us a threatening, compact team," Rio told MUTV.
"It was a very bad weekend. We've all been thinking about the reasons why it happened and how we want to pull ourselves together and get the result out of our minds."
With Arsenal in the FA Cup fifth round on Saturday and Olympique Lyonnais in the Champions League last 16 first leg the following Wednesday, Sir Alex Ferguson's men have little choice but to lift themselves.
Ferdinand says the healing process has already begun, but would be significantly aided by knocking Arsenal out of the cup at Old Trafford this weekend. "The best thing you can do is to come into training and just get focused on winning the next game, and that's what we're doing."