Former champion Advani, who has already pocketed eight world billiards titles, first eased past another ex-champ David Causier 4-0 in the last-16 match to be one of the four Indians to enter the last-8.
Kothari and Punjab cueist Alok Kumar also got past their respective opponents without losing a single frame in the pre-quarterfinals.
Maharashtra ace Dhruv Sitwala though had to work hard for his 4-2 win against fellow country and state mate Nalin Patel.
The party though continued for India, as national cue sport poster boy, Advani lived up to his reputation as the Bangalore ace humbled Alok 4-0 in the last-8 encounter.
Kolkata's Kothari also continued his surge as he made short work of Ian Williamson 4-0 to set up a last-4 clash with Advani.