Manchester United's defensive problems have deteriorated after Rio Ferdinand limped out of Sunday's 2-2 draw at Middlesbrough.
United are already without Nemanja Vidic for at least the next two weeks and Sir Alex Ferguson opted to play with Wes Brown alongside Ferdinand at the Riverside Stadium while John O'Shea started at right-back.
Sir Alex Ferguson told the club's official website: "We got a few bumps and bruises, but we'll assess things on Monday.
"Hopefully Rio's injury isn't serious. He was limping for quite a while and the danger with carrying on with him was we weren't going to get a full performance level from him."
Meanwhile, the veteran Scot thought his side's exciting draw on Teesside was a point won rather than two points lost as the battle for the Premier League title intensified.
"We could have lost the game," he admitted. "They had some chances and our defending was a bit haphazard at times.
"But on the other side of it, we could have won the game. Some of our football was terrific and we looked very strong and in control when we took the lead.
"Wayne Rooney was wrongly flagged offside when he was clean through just after that and when they got their equaliser it became a great game of football.
"It was end-to-end and both teams deserve great credit for producing a performance like that at this stage of the season.
"It could turn out to be an important point and our goal difference is very good as well. But we can't take anything granted.
"I said some weeks ago that the most consistent team will win it and hopefully it turns out to be us."