Ashleigh Barty surprised the tennis world when she announced her retirement this week, with the reigning Wimbledon and Australian Open champion walking away from the sport aged just 25.
Barty has been the WTA world number one for more than two years and there wasn't so much as a suggestion she was planning on quitting, so to say the tennis world is reeling from the news is no exaggeration.
However, given the illustrious names who have retired early, maybe we shouldn't be that shocked after all.
When Kim Clijsters burst onto the WTA scene as a teenager it was obvious the women's game had found a major talent.
She possessed brilliant power and accuracy from the back of the court at a time when serve-volleyers were all the rage.
By the time she was just 23, Clijsters had topped the WTA world rankings and won the US Open. Sadly, she had also been beset by injuries.
Fortunately for tennis, after two years in retirement, Clijsters was able to return to the game. Not only that, but she was able to pick up where she left off.
In 2009, the Belgian became the first unseeded women to win the US Open - four years after her initial triumph - and she added two more Grand Slam titles before retiring again in 2012, aged just 29.
Early retirements of brilliant Belgian tennis players was seemingly in fashion in the 2000s, with Justine Henin also walking away from the game.
Henin's retirement was eerily similar to that of Barty. She was 25 years old, had established total dominance of the women's game, was the long-time world number one, and no one saw it coming.
In 2008 when Henin retired, she was a seven-time Grand Slam winner having won every major except Wimbledon.
She was set to be the defending champion at both the French Open and US Open that year, yet she quit two weeks before Roland Garros.
"I am leaving as the world No.1 and that is important as it is always better to go out at the top," she said. "I leave without any regrets and I know it is the right decision."
Henin did make a brief comeback 16 months later, but never reached the same heights again and retired for a second time in 2011.
As brilliant as Martina Hingis was - and we should never forget it - hers is a cautionary tale for all young players.
Hingis was the youngest Grand Slam champion of all time at 15 when she teamed with Helena Sukova to win the Wimbledon doubles.
A year later, she won three of the four Grand Slam singles and was beaten in the final of the other, the French Open.
She picked up singles Grand Slam titles in each of the next two years too, meaning she won all five of her Grand Slams as teenager.
However, her success didn't stop there, and ultimately that may have been what cost her. While most players who reach a certain level focus on singles competition, Hingis was a prolific doubles player too.
While she was at her peak she also won eight Grand Slam doubles titles, meaning she was the world number one for both singles and doubles as an 18-year-old.
Sadly, playing that much tennis took its toll, and by the age of just 22 Hingis retired, admitting she felt too much physical pain while playing due to a series of injuries.
Hingis returned to tennis on a part-time basis and was still winning doubles titles as recently as 2017, but burnout definitely denied her the chance to become the all-round great her talent deserved.
When talking about shock early retirements in any sport, never mind just tennis, the name of Bjorn Borg is arguably the predominant name on the list.
Borg was the undisputed king of Wimbledon and a veritable global sporting superstar in the 1970s. He won Wimbledon five times in a row and six titles at Roland Garros too.
He also contributed to one of the greatest rivalries in sporting history, with his 'fire and ice' battles with John McEnroe some of the most brilliant contests imaginable.
In 1983, though, aged just 26, Borg sensationally walked away from the sport.
The Swede appeared to have simply fallen out of love with the game, telling the New York Times while announcing his retirement: "When you go out on the court, you should say this is great, I'm going to hit the tennis ball, I'm going to try to win every point, and I like to make a good shot.
"If you don't think and feel that, it's very difficult to play."
Like everyone else who retires from tennis early, Borg did attempt a comeback. It was eight years later, when he was in his mid-30s and struggling a little financially.
He entered the 1991 Monte Carlo Masters, turned up with his wooden tennis racket, got a Welsh karate expert as his coach and was well-beaten.
That comeback attempt lasted two years and failed to yield a single win. In fact it took him ten matches to even win a set.
A-Rod, as he was known, was expected to be the next big American male tennis star off the conveyor belt.
The US had produced the likes of Arthur Ashe, Jimmy Connors, Pete Sampras, Jim Courier and Andre Agassi and that torch had been passed to Roddick at the turn of the century.
Roddick reached world number one and won a major, the 2003 US Open, but in truth the game had changed around him. The balls and courts were tampered with to hold back the big servers - Roddick's primary weapon - and as a result he was never the dominant force he could have been without the alterations.
He was still a quality player, though, and he came to within a whisker of beating Roger Federer to the Wimbledon title in 2009.
Three years later, though, on his 30th birthday, Roddick announced his imminent retirement. Thirty may not sound especially young, but it's worth remembering that Roddick is a year younger than Federer, who was still winning Grand Slams at the age of 37.
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