Nick Kyrgios once said there was "zero chance" he would be playing tennis into his 30s.

But it was at the age of 31, while attempting another comeback from serious knee and wrist injuries, that he tested positive for a metabolite of cocaine at June's Mallorca Open.

In a post on social media, Kyrgios said it was a "huge mistake" for which he takes full responsibility.

But he added that recent injuries - he has only played eight tournaments and won two matches since the start of 2023 - have taken a huge toll on him.

"Coming to terms with being near the end of my career has been harder than I ever imagined," he added.

Kyrgios will not be able to play until his case is resolved because of a mandatory provisional suspension.

But although he faces a potential ban of up to four years, his suspension would be limited to a maximum of three months if he can prove the drug was taken out of competition.

The Australian has achieved more than most on the sporting stage. As a 19-year-old in 2014 he stunned then world number one Rafael Nadal on his Centre Court debut, and finished runner-up at Wimbledon eight years later.

At his best, Kyrgios is a flamboyant and athletic shot-maker with flair, touch and an explosive game.

But he can also be destructive and verbally abusive, and has regularly struggled to sustain the levels of professionalism and abstinence needed for a prolonged stay at the very top.

In 2015, Kyrgios was given a suspended 28-day ban for making lewd remarks about Stan Wawrinka's girlfriend during a match in Montreal.

A year later, he was banned for eight weeks for his behaviour - including a "lack of best effort" - at the Shanghai Masters. This was reduced to three weeks after he agreed to consult a sports psychologist.

2019 was the nadir. Kyrgios was defaulted from a match at the Italian Open for hurling a chair on to the court, and was later fined $113,000 for verbally abusing umpire Fergus Murphy in Cincinnati.

The ATP later issued a suspended 16-week ban for a "pattern of behaviour related to his verbal abuse of officials and/or spectators" over the previous 12 months.

Nick Kyrgios walks off with the Wimbledon singles runner-up trophy after losing the 2022 final to Novak Djokovic

Nick Kyrgios reached his sole Grand Slam singles final at Wimbledon in 2022, losing to Novak Djokovic

Kyrgios described 2019 as the "lowest point of my career" when interviewed for Netflix's Break Point documentary series.

"I was drinking, abusing drugs. I lost my relationship with my family, pushed all my close friends away," he said.

"Being bullied at a young age for being short and fat and brown scarred me for sure."

Kyrgios said he wore a compression sleeve to cover up self-harming scars on his arm and spent time in a psychiatric hospital in London to try and "figure out my problems".

He separately spoke about being forced out of a pub in Wimbledon Village by his agent in the early hours of a match day, and told Louis Theroux in 2024 that he would sometimes have "20 to 30 drinks" before playing the next day.

He has confessed to playing too much basketball - including for an hour before he beat David Ferrer in the 2017 Cincinnati Masters semi-finals - and has often said he has been unable to "dedicate" his life to tennis.

"I just enjoy doing whatever I'm doing," he said.

"I don't eat well. I don't train just for tennis, I train just for a general happy living - I know it sounds ridiculous, but I play a bit of tennis on the side."

Nick Kyrgios and Thanasi Kokkinakis pose after winning the Australian Open men's doubles title in 2022 Nick Kyrgios (right) and good friend Thanasi Kokkinakis won the Australian Open men's doubles title in 2022

In 2023, Kyrgios admitted assaulting ex-girlfriend Chiara Passari by pushing her on the pavement during a row in Canberra. The magistrate called the incident "a single act of stupidity or frustration" when sparing him a criminal record.

Then two years ago he publicly distanced himself from controversial influencer Andrew Tate, who is currently fighting extradition to the UK on charges including rape and offences related to sex trafficking.

Kyrgios told the BBC he had "deleted posts, unfollowed him and gone to all lengths to distance" himself from Tate.

The current world number 919 will now step away from public life for the next 28 days to "do the work and come back better".

The legal process could take many months - and Kyrgios is no fan of tennis' anti-doping system.

Describing the system as "awful," he made clear repeatedly his opinion that both Jannik Sinner and Iga Swiatek received overly lenient bans after their recent high-profile doping cases.

"Sad day for tennis. Fairness in tennis does not exist," Kyrgios wrote after Sinner accepted a three-month ban for testing positive for clostebol.

But if he does decide he wants to continue his career into his 30s, much will rest on the process of which Kyrgios has been so critical. (BBC)

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