Khan led 3-1 from where Asif recovered to make it 3-3 but the Indian held his nerves better in the decider to win 4-3.
After the match, Shahbaaz admitted that he felt under pressure while playing against the defending champion but he shut that thought out of his mind.
In first two frames, Shahbaaz dominated and played a brilliant game to gain a 2-0 lead. Asif countered with a break of 65 in third frame but Shahbaaz pulled the next frame to retain the lead.
"The decider was my last chance and I did not want to do any silly mistake. I kept my calm and waited for the opportunity. When I got, I capitalised," Shahbaaz said.
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Next he would be up against Pakistan's Shahid Aftab.
"It doesn't matter that I have beaten the world champion, next match is a new match and I have to play frame to frame, ball to ball," the Indian said.
Results (Last-64)
Men:
Shahbaaz Adil Khan (India) beat Muhammad Asif (PAK) 4-3 (76-34, 65-15, 34-80(65), 66-16, 23-75, 23-67, 71-07).
Shahid Aftab (PAK) beat Brijesh Damani (IND) 4-1 (66-22, 68(55)-16, 39-51, 56-34, 69(69)-55).