London (AFP) - Despite six knee surgeries and a world ranking that once nose-dived out of the top 1,000, Jason Kubler always believed he could make the tennis grade, maybe just not at Wimbledon.
The 29-year-old Australian reached the last 16 on Saturday with a five-set win over fellow qualifier Jack Sock.
His three victories at the All England Club this week are his first in the main draw of a grass-court event.
It is a scenario that would have seemed unlikely six years ago when he was off tour for an entire year following another bout of knee surgery.
There had already been a series of operations in his teens as a consequence of a hereditary knee condition.
"I've had five on the left, one on the right," said former world junior number one Kubler, matter-of-factly.
To protect his troublesome knees, he even played exclusively on clay courts from 2012 until 2015.
If that was not dispiriting enough, he then sat out an entire year between 2016 and 2017 to rest after another surgery.
At the end of the 2016 season, Kubler was down at 1,063 in the rankings.
"There's definitely been tough times.But I made a promise to myself when I had my last knee surgery, I really just wanted to enjoy what I'm doing," he said.
"Obviously it's been an up-and-down sort of career for me but I can definitely look back and go 'I've enjoyed the tennis'."
'I didn't have money'
During his year out, Kubler turned to coaching and acting as a hitting partner for other players to make ends meet.
That's when he came close to quitting his professional career.
"I probably did that for two or three months when I didn't have so much money," said the world number 99.
However, he performed well enough in low-key tournaments, which opened a wild card door at the 2018 Australian Open, eight years after he had first appeared in his home Grand Slam.
"If I didn't do as well back then, I doubt I would have kept going.I didn't have any money and not to brag, but I was doing all right with the hitting and the coaching stuff.
"Obviously I'm happier doing this sort of stuff."
Later in 2018, he made the first round at Wimbledon after coming through qualifying and the second round of the US Open.
This year, he reached the second round as a qualifier at the French Open.
He did not play a grass court event in the run-up to Wimbledon but his knees held up well on Saturday.
At four hours and 15 minutes, his 6-2, 4-6, 5-7, 7-6 (7/4), 6-3 win over Sock was the longest match of the men's tournament so far.
"This is a great moment for me and hopefully I can keep doing similar things," he said.
"But I definitely don't feel sour about what's happened.Maybe if I had handled situations differently when I was younger, maybe this could have come earlier."
Next up for Kubler is a last-16 clash with US 11th seed Taylor Fritz on Monday.
The pair met in the second round of the US Open in 2018 when Kubler was injured again, this time after rolling his ankle.
"When he's healthy, has a chance to play a lot, get the game going, he's a really good player," said Fritz.
Whatever the result Monday, Kubler's bank balance will have a healthier appearance.
By making the last 16, he is guaranteed £190,000 ($230,000).
