Nick Kyrgios’ return to the Australian Open is over after he and Thanasi Kokkinakis stopped playing while trailing in the second set of their first-round doubles.

Thanasi Kokkinakis says a doctor advised him not to play before he and Nick Kyrgios retired injured in the men doubles first round 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.

Thanasi Kokkinakis says he feels like he’s “letting people down”, with the doubles reunion of his 2022 Australian Open winning partner Nick Kyrgios “unlikely” after he suffered a recurrence of a pectoral injury in his second round loss at Melbourne Park.

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.

After a brutal five-set defeat on Wednesday evening, Thanasi Kokkinakis admitted it was "unlikely" he would back up to play doubles with good friend Nick Kyrgios. But against the odds, the 'Special Ks' walked out on John Cain Arena on Thursday night for their first-round match.