Joshi uncorked an unfinished 99 and followed it with two unfinished century breaks en route to resting on a comfortable 3-1 cushion, which reflected his devastating form. It served as a stern and rather early warning to Advani, who had experienced a huge scare before escaping to a four-point triumph over Joshi in the Nationals.

But Advani capitalised on Joshi's unbelievable blemishes, which included bungling an easy top pocket red in-off and a soft screw in-off in the crucial sixth game, to make the most of the chances that came his way.

The experienced Joshi maintained the pressure in the deciding seventh game but again muffed a cannon that allowed Advani to return and construct an unfinished 83 break to shut out his challenge and seal a place in the semi-finals.

"Joshi played a brilliant game today and I think this was the best match of the tournament. I have a lot of respect for him and I could not ignore the fact that he was the defending champion, which put me under a lot of pressure," explained Advani, who has now beaten Joshi on four occasions from as many clashes in recent contests.

"As the defending champion, Joshi was familiar with this format. The only way I could help myself was to build significant breaks and I think I just managed to squeak through."

"I had reason to be happy with the big breaks that gave me a dream start. But I missed those easy chances in the sixth game and I think that's where my fortunes changed," admitted a disappointed Joshi.

In another quarter-final, former world and Asian champion Ashok Shandilya overcame indifferent form to prevail over the formidable Aung San Oo of Myanmar 4-2.

Earlier, B. Bhaskar of India and former IBSF World champion C. Praput of Thailand qualified for the quarter-finals and occupied the seventh and eighth slots.

Results (breaks in brackets):

Quarter-finals (best-of-seven games): Pankaj Advani (India) bt Devendra Joshi (India) 4-3 [20-102(99 unf), 100(58 unf)-0, 0-101(101 unfinished) 6-101(101 unf), 101(101 unf)-0, 100(59 unf)-50, 102(83 unf)-0]; Ashok Shandilya (India) bt Aung San Oo (Myanmar) 4-2 [12-100(60), 100-50, 101(60)-72, 60-100(56), 101(101 unf)-7, 100(79)-42].

Round-robin qualifying (for 7th & 8th positions): C. Praput (Thailand) bt S. Thawat (Thailand) 3-2 [102-67, 100(88 unf)-5, 64-101, 43-100(58 unf), 101(51)-58]; B. Bhaskar (India) bt C. Praput 3-0 [101(99 unf)-4, 100(57)-85, 103(54 unf)-82]; B. Bhaskar w/o S. Thawat.