Manchester United manager Jose Mourinho has revealed that Wayne Rooney is unlikely to be fit for his side's New Year's Eve clash with Middlesbrough at Old Trafford.

Rooney was an unexpected exclusion in United's squad to face Sunderland this afternoon having picked up a muscle injury.

Mourinho insists that the problem is not a serious one, but doubts that Rooney will have recovered in time for the visit of Boro.

"Honestly, I don't think so. I hope so. I would like. He is always a player I would like to have, but I have my little doubts. Let's see the evolution," Mourinho told reporters.

"It is a strained muscle. I don't know if in English the name is the same as in Portuguese. It is a deep muscle and it is surrounded by others. You can have an injury there and still be able to move well, but we was not feeling very confident. So it is not a big deal, but in four days I have my doubts."

Rooney is currently one appearance short of 450 in the Premier League and one goal shy of Sir Bobby Charlton's all-time Manchester United record.