United have been in mediocre form by their standards so far this term but were boosted by the return of Ronaldo as a substitute in Wednesday’s goalless Champions League draw with Villarreal.

The Portuguese winger had been out since undergoing ankle surgery in July, but he is expected to start against Chelsea and has warned United’s title rivals that he is ready to strike back if they attempt to muscle him out of this weekend’s crucial clash.

“I know that the attempts to intimidate me on the pitch will start again immediately – but everyone finds sooner or later that it is difficult to make me lose my rag,” he told The Sun.

“I’ll be booted again but I will not kick out when it happens. I’m tough and, again, it’s all just part of the spectacle.

“I’ll do my damage as usual by paying them all back with my goals.”

Ronaldo also played down criticism of United’s stuttering start to the season, which has seen them win just a single game in six, adding: “There’s no problem at all with our form. Last year we started like this, look how we ended up.”