Rooney sustained the bruised toe during the second half of United’s 1-1 draw against holders Bayern in the Champions League quarter-final first leg at Old Trafford on Tuesday.
It was hoped Rooney would recover in time to lead the United attack at St James’ Park, but boss David Moyes has revealed the injury is yet to respond to treatment and the England striker is now set to go for a scan to see if there is further damage.
“Wayne’s got a badly bruised toe,” Moyes told MUTV on Friday. “He picked it up in the game the other night.
“Whether we were going to play him or rest him, it doesn’t matter.
“He’s got a terrible toe and not only will it be a problem for this game, it could be a problem for the Munich game as well on Wednesday. So we need to monitor it.
“We’ll get him treatment all over the weekend and see if we can speed it up.”
Rooney’s absence against Bayern would be a massive blow to United’s hopes of progressing to the semi-finals as they are already without Dutch striker Robin van Persie, who has been hit by a knee problem.
With five goals in six games last month, Rooney has been in fine form of late, but now the likes of Javier Hernandez and Danny Welbeck may well have to step up to the plate in Munich.
Moyes has suffered bad luck with injuries throughout his first season in charge, but he refused to complain about this latest setback.
“It’s football. You look at what Wayne has done for us in the last league games for instance,” he said.
“Against Aston Villa he scored two goals. There was a couple at West Ham including that special goal.”