Tennis: Nick Kyrgios erupts and smashes rackets after US Open quarter-final defeat by Karen Khachanov

Nick Kyrgios smashes his racket after being defeated by Karen Khachanov. Photo / Getty

Nick Kyrgios was sent packing from the US Open on Wednesday at the hands of Karen Khachanov in a five-set thriller.

The quarter-final showdown went down to the wire, but in the end it was the Russian who emerged victorious as he claimed the 7-5 4-6 7-5 6-7 6-4 victory. It set up a semifinal showdown with Norwegian Casper Ruud.

Kyrgios entered the contest as the favourite to take out the final Grand Slam of the year after his dominant win over number one seed Daniil Medvedev.

But it wasn't to be and Kyrgios let his frustrations boil over immediately after congratulating his opponent at the net.

In scenes we haven't seen out of the previously volatile Aussie for many months, Kyrgios destroyed two rackets courtside.

"That's not great, that's not great at all," Todd Woodbridge said on the Channel 9 coverage after watching the replay.

His outburst following the contest didn't sit well with fans who were watching on.

CNBC journalist Jude Sannith wrote: "Am I terrible person if I say that I'm really glad Kyrgios did not win? That behaviour is disgraceful & has no place in ANY sport. And just the fact that spectators and some pundits romanticise and encourage it, saying "it's good for the game" makes it worse."

Sportskeeda tennis writer Musab Abid wrote: "Nick Kyrgios embarrassing himself and the sport for the 7439th time."

The Age's chief reporter Chip Le Grand wrote: "This is a grown man, apparently."

Others however pointed to the outburst as a sign Kyrgios knew he had just blown a golden opportunity and showed he truly cared and was passionate about his job.

Tennis journalist Jose Morgado wrote: "Nick, more than anyone, knows that he just lost the biggest chance of his career. Tough, tough one for someone who finally seems to care about his job."

ABC broadcaster Corbin Middlemas wrote: "actually like this... from a guy once questioned about how much it all meant to him... sure there's another lesson in the character arc about handling disappointing etc. but one thing at a time."

Tennis writer Ben Rothenberg wrote: "Kyrgios will rue that one, but the first time being the favorite to win a Slam is no small challenge. I just hope that, when he plays again next, Kyrgios focuses on himself rather than obsessing over whether or not his support team is adequately vocal throughout. Got so, so old."

Kyrgios was on the back foot after losing the first set and appeared to be nursing a niggling leg injury, calling for a medic after the first set.

"I can't walk without pain," he was overheard saying.

The Australian later told his box: "I don't want to f****** play through this s***."

But Kyrgios managed to shake off the injury concern, playing through the pain and winning the second set to even the scores.

However, Khachanov quickly returned serve by winning the third set, putting himself one set away from booking his spot in the semi-finals.

Kyrgios then hit back, going to another level deep in the fourth set to win the tie-break and force a decider.

But despite having the advantage of serving first in the fifth set, Kyrgios was immediately broken in the opening service game and never recovered.