DANNY Welbeck left the Etihad Stadium wearing a protective boot on his ankle following Manchester United's 1-0 defeat by Manchester City.
Welbeck was caught by a nasty challenge from Nigel de Jong in the second-half, which sparked a furious touchline row between Alex Ferguson and Roberto Mancini.
It is not known whether he sustained the injury in that incident.
Ferguson was certainly not happy with De Jong's challenge, nor the manner in which Mancini was talking to fourth official Mike Jones. Jones stood between the pair during the row to prevent it spilling over before they were eventually pulled apart by members of their respective backroom teams.
"He refereed the game," said Ferguson. "He was out on that touchline the whole game haranguing the referee, the fourth official and the linesmen.
"The minute I come off the bench for a bad tackle by De Jong on Welbeck, he was out again. He can't have it both ways. He's been complaining about referees this season but he won't be complaining tonight that's for sure."
Ferguson will have no doubts over where United lost their Premier League title if City win their next two games - the loss of two late goals against Everton, when the sides drew 4-4 two weeks ago.
The Red Devils will relinquish their crown if City win their final two matches, at Newcastle and then at home to QPR a week later.
Vincent Kompany's header in first-half stoppage time did the damage, with United finding nothing in response.