Manchester United boss Jose Mourinho says skipper Wayne Rooney 'hid' an injury during the win over Fenerbahce as the striker was keen to play 90 minutes.
England record goalscorer Rooney was recalled to the Red Devils' starting XI in the Europa League on Thursday evening but has not travelled with the squad for their match against Chelsea this afternoon.
"Rooney got injured in the last training session," Mourinho told Sky Sports.
"He was feeling it in the game against Fenerbahce but he was keen to play for 90 minutes so he hid it.
"Then he felt it in training, so he couldn't come [to Chelsea]."
Mourinho returns to Stamford Bridge for the first time since being sacked in his second spell in charge of the Blues, and admits it's an emotional occasion, but insists he will try and treat the fixture the same as any other.
"This is a game," he added. "I have to think that it is just a game. It's a big game for us because it is against an important team that has the same objectives as we have. But it's a game.
"I have to try and treat it the same. I played a few times against Porto, I never did against Inter or Real Madrid but maybe one day I will.
"I have played twice against Chelsea and this is the third time. I would lie if I say it's exactly the same, it's not from an emotional point of view, but I have to try and make it so."
Mourinho also said it was not necessarily an advantage to know so much about some of the player on the other team.
He said: "Maybe it's not because when you know them so well maybe you try to focus so much on their qualities.
"If we are not balanced we pass on too much information to our players and they focus more on the opponents than our way of playing.
"So I try to use a selection of what I know from them and not make our players think too much about them but focus more on us."
