London, Jan 11 (IANS) Defending champion Ronnie O'Sullivan has withdrawn from the Snooker Masters on medical grounds, the World Snooker Tour revealed on Friday. The annual invitation tournament featuring the Tour's top 16 players opens on Sunday at Alexandra Palace in London. O'Sullivan, 49, was due to face John Higgins in the tournament's opening match.

O'Sullivan's withdrawal comes after he exited a Championship League event in controversial circumstances. During a defeat to Robert Milkins, O'Sullivan angrily struck his cue against the table after failing to make an easy pot, reports Xinhua. The Briton's place in the Masters will be taken by Australia's Neil Robertson, who was ranked in 17th position at the seeding cutoff after the UK Championship.

China's Ding Junhui was drawn to play against veteran Mark Williams in the first round on Monday. The tournament's two other Chinese players, Si Jiahui and Zhang Anda begin their campaigns on Tuesday and Wednesday respectively, with Si facing Mark Allen, and Zhang locking horns with Kyren Wilson.

Born in Wordsley, England, O'Sullivan, a seven-time snooker world champion and widely recognised as "The Rocket," took Hong Kong residency earlier this year under the Quality Migrant Admission Scheme, as announced by the immigration department.

The 49-year-old is widely recognised as one of the most talented players in snooker history. He has won the World Snooker Championship seven times, a modern-era record that he shares with Stephen Hendry. One of the most accomplished players in the sport's history, O'Sullivan has also won a record eight Masters titles and a record eight UK Championship titles, for a total of 23 Triple Crown titles, the most by any player.

One of the most renowned snooker players in the world, O'Sullivan turned professional in 1992 at the age of 16 after winning several amateur titles including the IBSF World Under-21 Snooker Championship.

O'Sullivan's other career highlights include three World Grand Prix titles, two Players Championship titles, four Welsh Open titles, two Scottish Open titles, two German Masters titles, four Irish Masters titles, two China Open titles, two Champions Cup titles, ten Premier League titles, four Champion of Champions titles, three Scottish Masters titles, and five Shanghai Masters titles.