Manchester United will face an anxious wait over Marcos Rojo after manager Jose Mourinho admitted he was concerned about a muscle injury sustained by the centre-back against Reading.

The Argentina international was replaced by Phil Jones after only 19 minutes of Saturday's 4-0 FA Cup win at Old Trafford, although he was able to walk down the tunnel.

WIth Rojo having enjoyed fine form at the heart of the United defence in the last two months and with Eric Bailly leaving for the Africa Cup of Nations, Mourinho has conceded that he is a little worried.

"I don't know. I have to wait a bit," he told BT Sport when asked about Rojo's condition. 

"A muscle is a muscle and we are a little bit afraid of it. Without Eric Bailly, it is more important.

"It would be so important for us to keep our central defenders fit for the month of January. But I prefer to wait. Chris Smalling and Phil Jones did a very good job for us."

Rojo, who has made 22 appearances in all competitions this season, is at least a doubt for United's EFL Cup semi-final first leg against Hull City and the Premier League clash with Liverpool next week.