Roy Keane and Patrick Vieira respective captains of Manchester United and Arsenal, remain doubts for Sunday’s Premiership showdown at Old Trafford.

Keane is struggling to overcome a flu virus, while Vieira picked up an ankle injury in Arsenal’s win over Aston Villa.

“Vieira is 50-50,” admitted Wenger on Friday.

“He took part in training this morning, when we protected his ankle a bit, but he’s better than expected.

“At the moment, it is looking good. If he doesn’t have a bad reaction to Saturday’s training, he will go a step further and then I will make a decision on Sunday.

“They first told me it was a three-week job, so I thought it was nearly impossible for him to play on Sunday. But to have him in the side for a big game, you know he has the experience and he’s seen it all.

“He has the impressive physical presence that you want as you know the commitment will be top-level. He can be technically good and physically strong.”

If Vieira misses out then Arsene Wenger may play 17-year-old Cesc Fabregas in his third game in nine days.

If Keane does not make it for United, John O’Shea may continue in central midfield, while Rio Ferdinand and Cristiano Ronaldo are set to return to the United starting eleven.

Arsenal are looking to extend their unbeaten run 50 League matches.