The 20-year-old from Inverurie, near Aberdeen, outfought the holder and world champion 17-14, 15-8, 11-15, 15-11 in an 81-minute second-round match. It was only the Pakistani player's fourth defeat in the last two years.
Two hours earlier England's Chris Walker had removed Rodney Martin, the second- seeded former world champion from Australia, 15-13 15-10, 5-15, 13-15, 17-15 in 68 minutes.
Nicol always believed Jansher was there for the taking. He said: 'I knew when I watched Jansher yesterday he was a bit flabby compared to when he beat me in the World Open in Karachi last November. He was explosive then but I went on tonight confident I could take him.'
The England No 1, Peter Marshall from Nottingham, reached the quarter-finals with a 53-minute 17-16, 15-4, 15-7 win over Austin Adarraga, of Spain.Reuse content