Kothari played his heart and never allowed Advani a comeback,prevailing 1000-644 in his last and 38th visit.
After his ninth visit, Sourav was trailing 256 against Advani's 352 but the national champion posted a break of 181 in his 18th visit to race past Advani.
Advani spilled a good opportunity in his 19th visit as he could only script a break of 65 points, not enough to get past Kothari.
In his 28th visit, Pankaj could manage a break of 106 and took his score to 644, trailing 305, which literally pushed him out of the tournament.
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Earlier in the day, Kothari had defeated Jaiveer Dhingra 751-432 in the last-16 stage.
Kothari was in good form and got on the job from second visit itself by posting first break of 77 followed by massive 208 in 13th visit to leave Dhingra way behind.
Advani had stormed into the quarterfinals after defeating compatriot Alok Kumar 751-547 in a last-16 match.
In another quarterfinal match, multiple-time world champion Peter Gilchrist made his way into the semi-finals by defeating the Englishman Robert Hall in an almost one-sided affair.
Robert in first two visits scored two breaks of 48 and 45 followed by 91 to score total 186 but after that Gilchrist ruled with breaks of 164, 83, 93, 144, 13 and 87 to take a giant leap towards win.
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