Nick Kyrgios returns a shot to Karen Khachanov on Wednesday in Mason, Ohio1. Photo: AFP

Nick Kyrgios stepped off court to smash two racquets and toss his shoes to spectators on Wednesday in a meltdown during a second-round ATP ­Cincinnati Masters loss to Russia's Karen Khachanov.

Eighth-seeded Khachanov rallied for a 6-7 (3/7), 7-6 (7/4) 6-2 victory over the volatile Australian, but the ­final set was close to farce, with Kyrgios engaged in a running dialogue with Irish chair umpire Fergus Murphy.

Kyrgios, who won his sixth career ATP singles crown two weeks ago in Washington, also complained last week in Toronto in an apparent dispute as to why he could not have a white towel during a match.

World No.27 Kyrgios, rarely far from controversy, was defaulted three months ago after throwing a chair as he quit a match in Rome.

The latest iteration of the Kyrgios saga erupted after he lost the second set to Khachanov. 

Sitting in his chair at the pause, Kyrgios suddenly announced he was going on a bathroom break, with Murphy telling him there was no time.

The Aussie walked anyway, carrying two racquets with him. Television showed him going through a stadium door partly made of glass and ­smashing his racquets before ­collecting them and walking back onto court.

All the while, he was nagging and occasionally cursing at Murphy.

Kyrgios calmly held his own at the start of the final set, producing a hold which featured three aces.

But it was the ice-calm Khachanov who took advantage, breaking for 4-2 and running out to a 5-2 margin.

Kyrgios, by now hardly in the match, double-faulted to hand over two match points and served up another double after saving a first match point.

He refused to shake Murphy's hand on the way off court and tossed his shoes and other soft articles into the crowd and handing his broken ­racquets to young fans before walking off.

At one point in the drama, Kyrgios stood at the back of the court, wrapping his racquet grip, which Murphy kept telling him he was not ready.

Kyrgios told Khachanov to go ahead and serve, but the Russian declined until all was in place on the Kyrgios side of the net.