Rooney a doubt for United
Interim manager Ryan Giggs said a number of United players have been struck down by illness, and are therefore unlikely to play at Old Trafford on Saturday.
Giggs said: "A few of the lads have had a bug.
"Anders Lindegaard has, and so has Wayne.
"Wayne has a tight groin also so obviously with the bug you have to be careful with that because his immune system is down.
"Wayne being Wayne, he wants to be involved so we will just monitor it over the next 24 hours."
Since United beat Norwich 4-0 in Giggs' first game in charge last Saturday, Juan Mata, Rooney and Lindegaard have backed the Welshman to be the club's long-term replacement for David Moyes, who was sacked last week just 10 months into a six-year contract.
United want a more experienced man at the helm though and have held discussions with Holland coach Louis van Gaal.
The former Ajax, Barcelona and Bayern Munich coach could be appointed early next week. Giggs is yet to decide whether he would like to be part of Van Gaal's staff.
"Nothing has changed. (This job) is just until the end of the season," Giggs said.
"We will chat when the season is over.
"The main concentration I have is on the Sunderland game and then after that the remaining two games.
"I have a lot to think about - whether to continue playing...
"But my concentration is just on now. We will see what happens at the end of the season."
Giggs has been handed a boost ahead of the Sunderland game with the news that Robin van Persie is back in training.
The Dutch striker has been out with a knee injury since scoring a match-winning hat-trick in United's victory over Olympiacos on March 19.
"Robin has looked good in training this week," Giggs said.
"We will see (after training) today whether he is ready for tomorrow."
Giggs is sure to receive another rapturous reception when he emerges from the tunnel - just as he did last Saturday when he confidently strode down the touch line in his official club suit.
Giggs is reluctant to swap the suit for his United kit, which opens up the possibility that the 40-year-old, who is out of contract in the summer, may never again play for the team he has supported all his life.
"I have kept myself fit, but I might not get back in (the team)," said Giggs, who has made a record 962 appearances for the club.
"The lads have been doing well. We will just have to wait and see."
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