Concerns are surrounding Nick Kyrgios’ knee after he lost round of 16 Murray River Classic tie against Borna Coric 6-3, 6-4 at Melbourne Park on Friday.

The Greek Australian player had problems with his left knee throughout the match and struggled to extract maximum power from his serve, and he also received tow code violations in the game that Coric broke him in the second set.

A trainer had to come out at the end of the first set to examine the player’s knee.

“I can’t serve without pain,” he told the trainer. “I can’t land on my leg. I am serving 170[km/h], instead of 220.”

Kyrgios went back onto the court with discomfort, and he seemed to indicate that he’d had a procedure done on the knee four-and-a-half earlier.

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The 25-year-old player said a “massive question mark” hangs over his Australian Open credentials.

“There’s a massive question mark for me, even if I was completely healthy (after) not playing in a year,” Kyrgios said. “It’s not easy to just turn around and prepare for an event just like that. It’s not like a tap.”

During the game there was some brilliant play with shenanigans as Kyrgios was warned by the chair umpire during the second set after smashing a racket and hurling it into the largely empty grandstand.