Edwin van der Sar will go for a scan on the calf injury that ruled him out of the FA Cup quarter final stalemate against Middlesbrough, although Sir Alex Ferguson is hopeful it is not serious.
The Dutchman pulled up in the warm-up at the Riverside and had to be replaced by Tomasz Kuszczak.
"Edwin's got a calf injury and he'll go for a scan on Sunday," said the Reds boss. "But hopefully it's not serious."
Despite the blow of losing the experienced goalkeeper, the boss was pleased with the performance of his deputy.
"Edwin's experience could have been vital during a couple of occasions," he said. "But I thought Tomasz Kuszczak was excellent. He made a couple of fantastic saves in the first half. He's a smashing young goalkeeper with great enthusiasm."
Rio Ferdinand and Nemanja Vidic are now unlikely to play against the Europe XI team on Tuesday, having picked up knocks in the game.
"The ones who need a game will get one in the UEFA charity match on Tuesday," said the boss, who mentioned Alan Smith as a player who will be given minutes to boost his match fitness. "Rio Ferdinand and Nemanja Vidic picked up injuries, they're doubtful for Tuesday."
One good aspect about the replay against Middlesbrough means that Paul Scholes will now be available for the league clash against Blackburn on 31 March as United look to clinch a ninth Premiership title.