Novak Djokovic will have to get used to being the “bad guy” following his disqualification from the US Open for striking a line judge with a ball, American great John McEnroe has said.

The world No. 1 was defaulted after a ball he swiped in frustration hit a female official in the throat on Sunday.

McEnroe, whose own behaviour frequently landed him in hot water with officials during his playing career, said Djokovic had buckled under pressure.

“The pressure just got to him. I think a lot has been going on off the court,” McEnroe told ESPN.

“It’s obviously affected him and whether he likes it or not, he’s going to be the bad guy the rest of his career.

“If he embraces that role, I think he could recover. He’s got a lot of things going for him, but this is a stain that he’s not going to be able to erase.”

After the premature end to his bid for an 18th Grand Slam, Djokovic left the grounds without attending a news conference and McEnroe, a four-time US Open champion, said the Serb should have faced the music instead of apologising on social media.

“You got to man up. It made no sense to me. In the past I’ve seen him take responsibility when he’s blown it. In this case it makes it even worse,” he said. “So what if he apologised on Twitter... that’s not good enough.”