Defending champion Pankaj Advani crashed out of the 78th National Snooker Championship after losing to club-mate Alok Kumar in the quarter-finals, in Chennai, on Monday.
He lost 59-27, 47-58, 63-31, 76-63, 44-73, 67-66, 66-58.
Another Petroleum Sports Promotion Board (PSPB) cueist, Aditya Mehta, with two century breaks, also progressed to the semi-finals.
The day's proceedings featured two promising youngsters, Neeraj Kumar of Railways and IM Manudev of Karnataka, making their maiden entry into the last four stage.
Neeraj got the better of Rafath Habib (also of Railways) 43-82, 59-29, 66-58, 68-58, 40-65, 41-50, 55-47, 14-76, 45-29, while Manudev defeated Manan Chandra (PSPB) 15-79, 68-31, 59-12, 43-74, 66-25, 33-79, 85-0, 70-43.
In Tuesday's semi-finals, Neeraj will play Alok Kumar, while Manudev will take on Aditya Mehta.
Advani, who has been in good nick throughout the championship in billiards and in the earlier two rounds in snooker, was off colour and played poorly.