ATP Cup results: Nick Kyrgios v Stefanos Tsitsipas meltdown video

Nick Kyrgios is used to being in the spotlight for his on-court behaviour – but this time it is the Australian superstar who has been forced to defend the shocking conduct of an opponent.

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Nick Kyrgios has leapt to the defence of Stefanos Tsitsipas following the Greek star’s meltdown that included accidentally hitting his father with a racquet in his ATP Cup loss to the big-serving Australian.

In an epic duel on Pat Rafter Arena on Tuesday night, Krygios beat world No.6 Tsitsipas 7-6, 6-7, 7-6 to seal Australia’s victory over Greece in the Group F tie.

Tsitsipas snapped after losing the first set, smashing his racquet wildly against a chair, and in the process hitting his father and Greek captain Apostolos in the arm.

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Stefanos Tsitsipas cracks his racquet and hits his dad in the process. Picture: Channel 9

It led to Apostolos storming off, and Stefanos being lectured by his mother Julia.

Tsitsipas was later docked a point for unsportsmanlike conduct after hitting a ball in the direction of his father on the Greek bench when trailing 2-1 in the second set.

Krygios, who stepped into the marquee singles match following Australian captain Lleyton Hewitt’s decision to rest Alex de Minaur, said he did not see Tsitsipas losing his cool.

But no stranger to on-court controversy himself, Kyrgios said it would be harsh to be overly critical of Tsitsipas.

“I don’t think you should be giving it too much attention or looking too far into it, to be honest,” said Kyrgios, currently on probation from the ATP.

“I’ve done some stupid things as well in the heat of the moment, so it was obviously an accident.”

Nick Kyrgios beat Stefanos Tsitsipas – and then leapt to the young Greek star’s defence. Picture: AAP

But there was nothing accidental about Kyrgios’ commitment against Tsitsipas. He again rose to the occasion playing for his country.

“Stef’s obviously a pretty good player, but … I served really well in big moments,” he said.

“I am really enjoying it. I think it’s a great event.”

With Australia having already qualified for the quarter-finals before their tie against the Greeks, it would have been easy for Kyrgios and the rest of his teammates to take a casual approach.

Nick Kyrgios says Australia are taking good momentum to the ATP Cup quarter-finals. Picture: AFP

But a third successive 3-0 clean sweep was further evidence the Australians mean business going into Thursday’s sudden-death battle against Great Britain in Sydney.

“We’re carrying some momentum going to Sydney. It could have been easy to take your foot off the gas,” Kyrgios said.

Australia’s three singles player – Kyrgios, de Minaur and John Millman – are all match-hardened, having played twice each during the group stages.

Hewitt said he had a “rough idea” which two of three would play singles today.

“But we’ll see how the guys pull up,” Hewitt said.

“It’s about the boys recovering as well as possible and getting ready for that (Great Britain) challenge.”