MELBOURNE - Nick Kyrgios and Thanasi Kokkinakis's bid to repeat their Australian Open doubles triumph of 2022 ended in retirement in on Thursday when the latter was unable to continue their first-round tie.

A seething Thanasi Kokkinakis has described his ongoing pectoral muscle issues as “physical and mental torture” after losing a five-set epic at the Australian Open.

Australian doubles pair James Duckworth and Aleksandar Vukic have eased into the second round of the men's doubles after opponents Nick Kyrgios and Thanasi Kokkinakis retired during the second set of their match on John Cain Arena.

Kokkinakis was forced to withdraw from the Adelaide International last week due to a shoulder injury, and his chances of a first-round win at the Australian Open looked dire. It led Aussie legend Woodbridge to question whether Kokkinakis should have been prioritising rest in the lead-up instead of playing exhibition events for the money.

Both Kyrgios (strained abdominal muscle) and Kokkinakis (right shoulder trouble) came into the match dealing with physical issues.

Winning the Australian Open in 2022, the childhood friends Nick Kyrgios and Thanasi Kokkinakis had a dream run at Melbourne Park but it ended in disaster on their return on Thursday.

Australian tennis star Thanasi Kokkinakis has stunned his opponent with an amazing act of sportsmanship at a critical moment of their second-round Australian Open clash. British No.15 seed Jack Draper was serving at two sets to one down, and trailing by a break in the fourth when he was about to be denied a certain point after a long rally.

Bumper crowds are expected to flock to Melbourne Park this weekend as ideal weather conditions greet some marquee matches.

It started with a Todd Woodbridge sledge towards Thanasi Kokkinakis and to no one’s surprise, Nick Kyrgios entered the room to support his mate.

Carlos Alcaraz has delighted his fans at the Australian Open by showing off his ripped physique during his victory on Sunday - but not everybody is happy about the crowd's response.

In an interview on the channel on Monday, Jones said he thought the comments had been "banter" and he had immediately made a private apology to the "Djokovic camp" once he realised they had not been taken in humour.