Ralf Rangnick shows Manchester United frustration as he hits back at Roy Keane over Cristiano Ronaldo comments

Beleaguered Manchester United boss Ralf Rangnick has hit back at Roy Keane after it was suggested all is not well with Cristiano Ronaldo.

The Portuguese superstar was not in the squad as the Red Devils were taken apart by Manchester City at the Etihad.

Veteran striker Ronaldo has been struggling with a hip problem, but Keane intimated pre-match that he feels something more may be going on behind the scenes.

And after a 4-1 loss that question was put to the United boss, who has struggled to impose his playing style since replacing Ole Gunnar Solskjaer.

Rangnick asked: "What did Roy Keane say?"

When it was explained to the German that the club legend had suggested Ronaldo may not really be injured, the interim boss gave an exasperated response.

"Well, I have to believe my medical department.

"Our doctor came to see me on Friday morning before training and told me Cristiano cannot train because of some problems with his hip flexor.

"The same was true on Saturday and that was why he couldn't be part of the squad."

Fellow striker Edinson Cavani DID train before the game but ruled himself out, and the Manchester United boss was asked if he was frustrated by that call.

Rangnick replied: "What does it help if I tell you it's frustrating? It's just a fact.

"If players tell the doctor and the medical department that they're injured and cannot play I have to accept it as a manager. I cannot force a player to play if he thinks he's not available because he has an injury.

"Look, Edi trained for the last three days. He trained well but he still felt after those three training sessions he's still not fit to play.

"This is a fact, as a manager I cannot force a player to play if he doesn't feel fit enough and well enough."