Sanam, ranked as low as 397, beat the home favourite Chung 7-5 6-1 the third round, which lasted in one hour and 24 minutes at Yeorumul Tennis Courts.
Sanam was trailing 1-4 in the opening set but turned the match on its head by reeling off four games on the trot to take lead.
Sanam stood out with audacious cross court winners. The fighting spirit kept the Chandigarh lad going despite making a poor start.
Sanam closed the contest when Chung failed to return a ferocious forehand from the Indian.
One more win would assure Sanam at least a bronze medal.