Before Nick Kyrgios, the enfant terrible of Australian tennis was Brydan Klein, who won his first Grand Slam match at 19 and then saw his career implode amidst a series of punishments for abusing opponents and umpires.
Now 29, Klein – a former Australian Open junior champion - plays under the British flag trying to enjoy the autumn of his career best he can.
He's mellowed slightly but still has the odd lapse. In 2017, there was disapproval when he earned a Wimbledon wildcard having just been fined £3,500 for unsportsmanlike behaviour at a warm-up tournament in Nottingham.
Nick Kyrgios exploded at umpire Fergus Murphy during his first-round match at Queen's
Despite the colourful image, the off-court Klein has charm, intelligence and a self-awareness about his past problems. His insight into 24-year-old Kyrgios is valuable as the modern Aussie bad boy also threatens to screw up his career.
He has slipped to number 39 in the world and after his latest defeat at Queens, a fourth defeat in six matches, he confessed to gaming until 3am before his match. He was also fined almost £14,000 for a rant at umpire Fergus Murphy and accusing a line judge of 'rigging' the match.
Klein gets the human unhappiness behind Kyrgios' worrying behaviour that fluctuates wildly between toddler tantrums and not appearing to try.
'Kyro is one of the most talented players of the last decade. When he cocks up and does something stupid, I know he regrets it. Same as I did when I was young,' says Klein about one of the most complex personalities in sport.
'When you are hot headed, late at night you stay awake really wishing you could change the day around. I think Nick gets homesick and doesn't like the grind of the tour week-in, week-out. He has to find a way of travelling and enjoying it.
'He likes the buzz of playing big matches, if he can find something outside the tournaments to like, you'll see his talent more consistently.'
One-time bad boy Brydan Klein believes Kyrgios is capable of improving his behaviour
Klein thinks the answer may be as simple, or not, as the love of a good woman. He still managed to shock the genteel natives at last week's Challenger event at Ilkley by bellowing 'stop playing like a jerk' to himself during his passage to the third round. But generally, he's far more in control when his better half from Canberra is over to visit.
'If Nick has a stable girlfriend he can travel and share experiences with, it will help a great deal,' he suggests.
