Nick Kyrgios lost his temper and was given a point penalty for his behaviour as he lost 6-3 6-4 to Borna Coric in the Murray River Open.
The Australian's spectacular implosion occurred in the second set, when he was warned for swearing before lobbing a smashed racket into the empty stands.
Kyrgios' problems began early on Friday as he struggled with a left knee issue and needed treatment midway through the match at the Australian Open warm-up event.
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"I can't serve without pain. When I land it feels unstable," local media quoted Kyrgios as telling a trainer between sets.
"I'll probably just play one more game. I'm serving at like 170(kph) instead of 220."

Kyrgios smashes racket, then launches it into empty stand

The 25-year-old, playing his first tournament in nearly a year due to the Covid-19 pandemic, soldiered on and was warned by the chair umpire for swearing at 4-4 in the second set.
After his serve was broken, he smashed his racquet and threw it into the empty seats.

Kyrgios: 'I don't care, I'm going to serve big and play big'

On Wednesday, Kyrgios had needed assurances from a tournament supervisor that he would not be fined by the ATP for his behaviour in the last round against Harry Bourchier before agreeing to play on.

'I’m not playing!' – Kyrgios walks off after time violation

With additional reporting from Reuters
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