Wayne Rooney on the bench against Zorya Luhansk

This was not a classic Jose Mourinho threat, more an admission that the escalating scrutiny Wayne Rooney faces is something the Manchester United manager is acutely aware of.

A decision on whether Rooney will start against Zorya Luhansk in the Europa League at Old Trafford has been delayed, for two reasons.

First, Rooney did not train on Tuesday owing to a back complaint.

Second — and perhaps more significantly — Mourinho believes his captain must sparkle the next time he pulls on a United jersey.

‘I think he really can’t afford to have a performance that is not really good,’ Mourinho said before a Europa League Group A clash he insisted his side must win.

‘Today was the first time he had a training session with the other players and that is the training session where the intensity and the complexity is obviously reduced because we have a game tomorrow. I’m here to protect him and not to put him in difficult situations.’

‘I was completely convinced about playing him from the beginning (but) with his situation in the last couple of days I’m not sure I will do that because of the situation you create for him.

‘I have to analyse if the best thing for him is to start the game (or) if he is not totally ready for it. So I’m going to discuss that with him and the medical staff.’

Rooney is in the squad to face a side who held Fenerbahce to a 1-1 draw a fortnight ago and who sit second in Ukraine’s Premier League, ahead of Dynamo Kiev.

It appears he remained vocal in the United dressing room despite being dropped for the weekend 4-1 win against Leicester City and team-mate Jesse Lingard believes that will ‘never change’, even if his role becomes redefined.

‘Wayne is a top-class professional, a top-class player,’ Lingard said. ‘He’s still got many, many years to go.

‘He’s an inspirational guy and a leader. He’s always going to be the same Wayne Rooney, the leader.

‘For every player, you’ve got to bounce back and I think he’ll do that. Obviously against Leicester the manager switched up the team, gave it a different dynamic, and we won the game but, with or without him, we are going to do the best we can as a team. We are a team and we’re going to stick together.’

Whether Rooney starts or not, United are treating tonight’s game with the utmost importance.

Mourinho insists only a win will do if they want to progress further after the defeat by Feyenoord in Rotterdam in their first group game.

‘It’s very important,’ said the manager. ‘If we don’t win we have four matches and I would say we have to win all the last four matches, which is difficult.’ Two different members of his backroom staff have travelled to watch a couple of Zorya’s recent games as United leave nothing to chance.