Tennis star Nick Kyrgios on Friday pleaded guilty to assaulting a former girlfriend, but avoided a conviction for what the magistrate called a "single act of stupidity".

The Canberra magistrate dismissed the assault charge against the 27-year-old Australian player.

Appearing in a Canberra court, the Wimbledon finalist admitted assaulting then-girlfriend Chiara Passari on January 10, 2021, by pushing her to the ground after a heated argument.

Passari lodged a complaint with police 10 months later, after they had broken up, lawyers told the court.

In a statement read to the court, Passari said she had been severely traumatised by the incident, experiencing severe weight loss, staying in bed day and night -- unable to sleep or form new romantic relationships.

Lawyers for Kyrgios had appealed to have the charge, one count of common assault, dismissed on mental health grounds, arguing it was an isolated incident and out of character.

Psychologist Sam Borenstein told the court Kyrgios suffered from recurring major depression, which included black periods, thoughts of self harm, insomnia, agitation and feelings of guilt.

Borenstein said the tennis star had relied on alcohol and drugs as a means of coping, but was now making progress in dealing with the issues.

"As we speak now his mental health has improved significantly," Borenstein said.

Magistrate Beth Campbell heard that appeal but ultimately dismissed the charge.

Campbell said Kyrgios acted poorly but the offence was not planned or premeditated and was a "single act of stupidity" by a young man attempting to extricate himself from a tense situation.

Kyrgios was said to have shoved Passari, who was preventing him from leaving her Canberra apartment.

"I do not record a conviction against your name, I do not find any necessity to place you on a good behaviour bond," Campbell said.

Squandered talents? 

Kyrgios had hobbled into court in Canberra with a pair of crutches and a brace on his knee, after suffering a "gruesome" injury that sidelined him at last month's Australian Open.

He was flanked by his current girlfriend Costeen Hatzi, an interior designer, and his mother Norlaila.

Kyrgios, who has clashed with media in the past, did not speak to reporters on his way into the building.

Canberra-born Kyrgios, known for his mercurial talent and on-court outbursts, has spoken publicly in the past about his battles with depression and the pressures of global tennis fame.

"I'm proud to say I've completely turned myself around and have a completely different outlook on everything, I don't take one moment for granted," he wrote on Instagram last year.

The case was adjourned in October, as Kyrgios prepared to play the Japan Open, so experts could prepare mental health reports for the court.

"There's only so much I can control and I'm taking all the steps and dealing with that off the court," Kyrgios said from Tokyo at the time.

Currently ranked 20th in the world, Kyrgios featured prominently in the first episode of Netflix's new Break Point tennis documentary.

The fan favourite won the Australian Open men's doubles crown with close friend Thanasi Kokkinakis last year but was ruled out of this year's tournament before playing a match.

His manager Daniel Horsfall said he had recently undergone surgery to remove a cyst inside his knee.

"The surgery went great, to be honest, we couldn't have asked for a better result," he told radio station SEN.

"He might be recovering faster than what we were expecting, so it's good news."

Kyrgios burst to fame as a 19-year-old in 2014, when he shocked the tennis world by beating Rafael Nadal to reach the quarter-finals of Wimbledon.

Often criticised for squandering his talents, Kyrgios reached the final of last year's Wimbledon, but was comprehensively beaten by Novak Djokovic.