Pankaj Advani's title defence was brought to an abrupt end by Myanmar's Kyaw Oo, who thrashed the Indian in the pre-quarterfinal match of the IBSF World Billiards Championships in Singapore on Friday.
Advani, only the second cueist to win both the world billiards and snooker titles, lost 2-4 to Oo, who had lost to the Indian in the preliminary round on the opening day of the tournament.
Oo will now play local challenge Peter Gilchrist, who thrashed Martin Goodwill of England 4-0 in another round of 16 match.
However, India had some good news in store with former champion Geet Sethi, Ashok Shandilya and Rupesh Shah advancing to the quarter-finals.
Sethi blanked Phil Mumford of England 4-0 and Shandilya carved out a 4-3 win against Aung Sang Oo of Myanmar.
Shah also impressed with his 4-0 victory against Frank Humphries of Australia. He will next play Praput Chaithanasakun of Thailand.
Dhruv Silwala, however, could not make it to the knock-out round after he finished third in his Group B of five players.