Hull defender James Chester is set to miss the FA Cup final after suffering a hamstring injury against Aston Villa on Saturday.
Chester came off just before half-time against Villa and although manager Steve Bruce was not willing to rule him out of the May 17 date against Arsenal, it looks highly unlikely he will be fit.
The centre-half was out for an 11-week period with a similar problem between September and December and appears to have aggravated the problem.
"The earliest reports on James look as if the hamstring that he's come off with, he's re-injured it. It looks bleak for the lad," said Bruce.
"We can't say until we scan him and know the extent but it doesn't look very good for him."
Sone Aluko is also sweating over his fitness after turning his ankle in training last week.
"Sone won't be available (for Manchester United) on Tuesday, it's touch and go for the cup final I'd have thought."
There was some good news from the Tigers treatment room, with long-term absentees Allan McGregor (ribs/kidney) and Paul McShane (ankle) progressing well as they eye Wembley.
"McGregor has got a hell of a chance the way he's going at the moment," added Bruce.
"McShane is coming along well too and we'll see how they progress in the next couple of weeks."