It was announced this week that four-time world champion Ronnie O'Sullivan will not return to the professional tour this season due to personal issues.
Mark Spitz
Following the 1972 Munich Olympics, at which Mark Spitz won all seven of his events, the legendary American swimmer announced his retirement at just 22 years of age.
He was bombarded with rewarding commercial offers following his success yet a return to the pool remained on the cards.
In April 1990, Spitz, who was then aged 40, attempted to qualify for the US swimming team for the Barcelona Olympics in 1992. He aimed to swim in just one event yet it was not to be as he failed to qualify for the Spanish Games.
Rocky Marciano
During the 1950's, American boxer Rocky Marciano held the heavyweight boxing title for four years. However, in a shock move following such huge success, he announced his retirement at the age of 31 in April 1956.
This followed a memorable bout in which Marciano faced one of his heroes, the former heavyweight champion Joe Louis. Marciano knocked him out in the eighth round.
He remains the only heavyweight boxing champion to ever retire undefeated and at the time had said he wanted to spend more time with his family.
Barry John
Welsh rugby legend Barry John was one of the most highly-respected players during his sporting career, yet it was a pressure which ultimately proved too much for the fly-half.
He was known as "The King" to his followers and his talents shone through most in 1971 when he was picked for the Lions tour to New Zealand.
However, the mounting pressure of constantly being in the public eye proved too much for him, as he retired from rugby aged only 27, a year after the Lions tour.
Michael Jordan
Leading basketball player Michael Jordan produced one of the biggest shocks in sport when he announced his retirement prior to the 1993-94 season.
The Chicago Bull wanted to pursue his dream of playing baseball and, in February 1994, aged 31, he signed a contract with affiliate of the Chicago White Sox- the Birmingham Barons.
However, this change of direction in his sporting career did not produce the success he had envisaged and he subsequently came out of retirement for the 1994-95 NBA season.
After the 1997-98 season, his contract expired leading Jordan to retire for the second time.
Remarkably though, he then returned to the court but, rather than playing for the Chicago Bulls, he joined the Washington Wizards between 2001 and 2003.
Steffi Graf
One of the most famous female tennis players ever, German Steffi Graf is another example of a sportsperson retiring whilst still in their prime.
Having won 22 Grand Slam titles, and after winning her 6th French Open Championship, Graf retired in 1999 aged 30.
There is no doubt that she was still near the top of her game, yet she struggled to remain motivated.
Annika Sorenstam
Turning to the golf course now and it was a strong wish to start a family that saw Swedish golfer Annika Sorenstam retire from the sport following the 2008 season.
During her career, she won eight LPGA Player of the Year Awards and accumulated 90 international tournament wins, including 10 majors.
Jim Brown
Jim Brown was one of the most well-known and respected running backs in the NFL. His retirement when he was just 29 following the 1965 season shocked his followers and Cleveland Browns fans.
He was regarded as still being at the pinnacle of the sport, being the league's career leader in rushing touchdowns (106) and in rushing yards (12,312).
Ned Jarrett
The NASCAR legend Ned Jarrett became the only driver to retire while still champion aged 34, in 1966.
His surprise decision followed a great season in 1965 and he earned a total of 50 victories in his career, placing him 8th on the all-time list.
Jarrett is on NASCAR's 50 Greatest Drivers list as well as having been inducted into eight Hall of Fames.
