Nick Kyrgios crumbles, sensationally retires from Shanghai Masters

Nick Kyrgios has sensationally quit his first-round match at the Shanghai Masters in apparent protest against the umpiring.

The volatile Australian stormed off after losing the first set 7-6 (7-5) in a tiebreaker.

Kyrgios's dramatic walk-off comes a year after he was suspended from the ATP Tour for tanking at the Shanghai Masters and leaves his immediate playing future in doubt once again. The 22-year-old had received two code violations for unsportsmanlike conduct and expressed his dismay at the chair umpire for copping a point penalty during the tiebreaker.

He was picked up on TV telling his courtside entourage he would stop if he lost the set, which he did.

The latest incident left commentators dumbfounded.

"What is it about Shanghai and Nick Kyrgios? Emotions getting the better of him and he's off," one said. "The next chapter of the Nick Kyrgios career unfolds."

Kyrgios was leading 4-2 in the tiebreaker before losing a rally and then copping his point penalty then gesturing to his box: "What is he doing? ... "

A commentator weighed in with: "He said if he loses this set, he's retiring. Not happy with some of the decisions the umpire is making regarding controlling the crowd."

When he'd had enough, Kyrgios called Johnson to the net, shook hands and then shook hands with the chair umpire without making eye contact.

Runner-up to world No.1 Rafael Nadal in the China Open final, Kyrgios had been making a run towards the season-ending World Tour Finals before handing Johnson a mid-match walkover.

He was sitting 15th in the Race to London, where the top eight players of the year will assemble for the prestigious round-robin event.

But he will now almost certainly come under serious scrutiny from officials for quitting a match at the very same venue where he was accused of not giving his best efforts 12 months ago.

Kyrgios also received two code violations during his loss to Nadal two days ago after losing his cool over an unfavourable line call in the first game of the final.

His rare, possibly even unprecedented, walk-off on Tuesday night prompted immediate criticism from tennis fans on Twitter.