Tennis firebrand Nick Kyrgios has returned serve at rising Norwegian star Casper Ruud, saying he’d rather watch paint dry than him play.

The pair have been engaged in a war of words since Kyrgios was infamously disqualified from his match against Ruud at the Rome Masters in May.

Kyrgios was defaulted during the second round clash after smashing a racquet, kicking a water bottle and throwing a chair.

Ruud said that Kyrgios should have been suspended for at least six months rather be put on probation for that time and lose the ATP points he’d earned in the tournament.

The fiery Australian, who is also offside with the world’s top two ranked players Novak Djokovic and Rafael Nadal, then mocked Rudd for celebrating on-court following the default.

It prompted world No.61 Ruud this week to call Kyrgios an “idiot”.

“I was happy and got 90 points and $50,000 in prize money so why wouldn’t I celebrate?,” Ruud said in an interview with Tennisportalen.

“It’s his problem that he’s an idiot on the court.”

On Thursday Kyrgios blasted back on Twitter saying that Ruud, who is Norway’s top player, wouldn’t dare criticise him to his face.

He also said Ruud was a no-name and played boring tennis.

“Hey @CasperRuud98 next time you have something to say, I would appreciate you say it to my face, I’m sure you wouldn’t run your mouth so much after that. Until then I will continue to rather watch paint dry then watch you play tennis, boring,” Kyrgios tweeted.

“But again, I also understand why you have to keep my name in your mouth, because people dont even realise that you play tennis goodluck in Milan champ x”

Kyrgios, the world No.30, was this week welcomed back into the Australian Davis Cup fold with captain Lleyton Hewitt saying he’d earned the recall.