The 32-year-old former world No 1, from Harrogate, secured a comfortable 3-0 win over his former Pontefract team-mate at the Meydenbauer Center in Bellevue, Washington.
He now lines up against Egypt’s world No 1 Elshorbagy later today for a place in the quarter-finals.
“Saurav’s been in great form,” said Willstrop, who is still on the comeback after undergoing surgery.
“I haven’t really got a lot of those tough matches under my belt so I’m absolutely chuffed to bits to be able to put that together like that really.
“You forget how to do it a little bit and you’ve got to relearn it which I’ve been doing for a few months now and it came together against Saurav.”
Elsewhere, there was dismay for Harr0gate-based Chris Simpson, who suffered a first round exit at the hands of 15th seed Stephen Coppinger, the South African winning 11-9, 11-7, 11-4.