A Sri Lankan journalist lights a candle in front of the grave of slain editor Lasantha Wickrematunge in Colombo on Wednesday, on the 11th anniversary of his death. International media rights groups have criticized Sri Lanka for failing to identify the assassins of Wickrematunge, a top anti-establishment editor. Photo: AFP

Stefanos Tsitsipas has laughed off a temper tantrum that saw him clip his father's arm while smashing a racquet, and said he is feeling "good with his game" heading into the Australian Open.

The hot-headed world No.6 lost his temper after dropping the first set to temperamental Australian Nick Kyrgios, who was on his best behavior, at the ATP Cup on Tuesday evening on his way to defeat.

He slammed his racquet into the Greek team bench, where his father and captain Apostolos Tsitsipas was sitting, catching him on the forearm.

It left his dad bleeding from a small cut, with his mother coming down from the stands to give him a talking to.

"It happened accidentally. I didn't mean to do it and straight away forgot about it and moved on from there," the 21-year-old said in the early hours of Wednesday morning.

"It happens. I wasn't aiming to do that, so it's just it went out of control, unfortunately."

Asked if he will be punished by his parents, he joked, "Maybe I'll stay in my room for three days, grounded by my father."

Despite his meltdown and loss to Kyrgios, Tsitsipas said he was happy with how he was doing heading into the opening Grand Slam of the year at Melbourne Park this month.

He has so far totted up just one win out of three, also losing to Canada's Denis Shapovalov in two tough tiebreaker sets while thrashing world No.7 Alexander Zverev.

"There's nothing I'm worrying [about] right now. I feel good with my game, with my physical [condition]," he said. 

"The only thing that might concern me a little bit is when I come close to matches I feel like I've lost this competitiveness within me. 

"I remember a few months ago I had the tendency to be more in the zone, really, really concentrated and knew what I was doing, playing very aggressive," he added. 

"Sometimes I feel like I get too passive and I'm not really into the match, which, I don't know, probably a few technical issues that I have to work on and not to think too much of my technique and work on my tactics more."

Tsitsipas, who made the Australian Open semifinals last year, will play at the Kooyong Classic exhibition event in Melbourne next week as he fine-tunes preparations for the Grand Slam, which starts on January 20.