Sobhy, the United States' number one, delighted the home crowd at the University Club of Chicago with a narrow 7-11, 11-9, 5-11, 11-5, 11-7 win over Annie Au of Hong Kong. 

She will take on world number two Nouran Gohar for a place in the last four, after the Egyptian eased past Belgium’s Nele Gilis 11-3, 11-3, 11-6.

"That was definitely tough, Annie came out firing and I think the ball in the first three games kind of suited her because it was a bit dead and she loves a good lob, drop" said Sobhy.

"I just told myself to fight for every point, to hustle, hustle, hustle and fortunately I did that and came out a winner."

Blatchford was the second American to progress to the quarter-finals, also requiring five games to overcome Egypt’s Nadine Shahin 8-11, 11-6, 11-3, 9-11, 11-9.

World number one Raneem El Welily is set to be her next opponent, with the Egyptian comfortably beating compatriot Salma Hany 11-6, 11-3, 11-6.

In the men's event, Spanish veteran Borja Golan booked his place in the quarter-finals following a 8-11, 11-9, 11-4, 11-9 win against Youssef Soliman of Egypt. 

"I’m so happy, I don’t think this moment is going to come for me again because I’m finishing my squash career," said Golan.

He is scheduled to take on Egyptian world champion Tarek Momen, who defeated another Spaniard, Pajares Bernabeu, 11-5, 11-4, 9-11, 11-5.

World number two Ali Farag and world number seven Diego Elias are set to go head-to-head, with Farag bettering fellow Egyptian Omar Mosaad 13-11, 11-5, 11-6.

Peru's Elias overcame Joel Makin of Wales 12-10, 11-9, 11-8.

The second half of the men and women's draw is scheduled for tomorrow, with quarter-final matches expected to take place on Monday (March 2).