Nick Kyrgios loses point after illegal act against Daniil Medvedev

It's common knowledge that just about anything can happen when Nick Kyrgios sets foot on the court, but nobody could ever have predicted the most bizarre of moments in his win over Daniil Medvedev at the US Open.

Having won the first set tie-break to start the fourth-round clash on a high note, Kyrgios quickly fell behind the World No.1 in the second set.

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Looking to regain his footing after Medvedev squared the match at one-set all, Kyrgios had a huge opportunity to get to break point and a potential 2-0 lead in the third set.

A dominant rally from Kyrgios at 30-30 left Medvedev with no other option but to throw his racquet at a powerful shot down the line, popping the ball straight up in the air and nowhere near crossing the net.

But Kyrgios threw away a certain point with a bizarre piece of showboating, running around the net to smash the ball back onto the court.

Despite his celebrations, it was inevitably ruled a foul shot by chair umpire Eva Asderaki-Moore and a point for Medvedev, which he quickly capitalised on to hold serve.

To say the tennis world was stunned by Kyrgios' decision would be an understatement, as few were able to find the words to describe what must have been going through his head.

"You can't do that, you cannot cross the net, the ball's not dead yet," Channel 9's Todd Woodbridge observed.

"What an error in judgement. That should have been break point. I've never seen anything like that in all my time in tennis. That is crazy."

On social media, fans were simply in disbelief.

Remarkably, the error didn't end up costing Kyrgios as he went on to break Medvedev on his subsequent service game.

He then capitalised on that break to win the third set 6-3 before storming into the quarter-finals with a 7-6 (13-11) 3-6 6-3 6-2 victory.

Nick Kyrgios fumes at chair umpire over service clock

Kyrgios and Medvedev were locked in a tight battle in the first set on Sunday when the Aussie was left fuming that he'd been hit with a time violation warning while serving.

The 27-year-old suggested that Asderaki-Moore was starting the service clock too early, particularly after a number of long rallies in hot and humid conditions.

"You are the only umpire that I've a problem in this matter," Kyrgios shot at the umpire.

"I get back from the box and there’s like six seconds. I’ve never had a problem with it at this tournament apart from with you."

Kyrgios is one of the fastest players between serves on tour and rarely gets pinged for falling foul of the shot clock.

Woodbridge pointed out that some umpires start the shot clock as soon as the previous point ends, while others give the players a couple of seconds of respite.

Spectators weren't happy with Kyrgios' complaints, loudly booing the Aussie star during his tirade.

However he regained his composure in the third set to go on and defeat Medvedev for the second time in three weeks and vault himself into the quarter-finals at Flushing Meadows for the first time.

The 27-year-old will play another Russian, Karen Khachanov, for a semi-final berth on Tuesday (Wednesday AEST).

with AAP

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