England's Laura Massaro and France's Gregory Gaultier were both knocked out of the Professional Squash Association (PSA) US Open at Drexel University in Philadelphia today.
Both competitors saw the defence of their titles come to a premature end as they bowed out during a dramatic day of quarter-final action.
Gaultier, winner of the NetSuite Open in San Francisco last week, let a commanding lead slip as he fell to a 3-1 defeat to Karim Abdel Gawad of Egypt.
The 33-year-old was in total control as he took the opening game 3-11 before opening up a 1-6 lead in the second.
After becoming irritated with a number of refereeing decisions, however, Gaultier's game slipped allowing Gawad to storm through to seal the match 3-11, 11-9, 11-7, 11-5.
"I think that is the best win ever in my career so far," said Gawad.
"Greg is the number two in the world and one of the most experienced players on Tour.
"Before today he had beaten me in the last eight matches we have played so it is my first win against him and that means a lot."
Gawad is now due to face England’s Nick Matthew for a place in the final after the 36-year-old defeated Egypt's Ali Farag.
Matthew never looked trouble as he sealed his place in the last four with a 11-8, 11-7, 11-8 straight games win.
Laura Massaro, the number two seed in the women's tournament, suffered defeat at the hands of Camille Serme of France in a five game thriller lasting 55 minutes.
Serme beat Massaro to win the 2015 British Open, the biggest win of her career, and she played with unwavering confidence in Philadelphia to end a spell of poor form.
She took the first game 11-8 before Massaro levelled things up taking the second 8-11.
Sixth seed Serme then took the lead again, winning the third game 11-2.
Once again, however, she failed to capitalise and lost the fourth 6-11 before taking the fifth and decisive game 11-6.
"To beat Laura, the defending champion, is a great win for me right now and it feels amazing," said Serme.
"i have worked hard lately at trying to change my mindset in all areas - in the gym, in practice - not just in matches, to try and push me even harder.
"Today I was trying to keep positive throughout the match and I think in the fifth the mental element was the key."
In the day's other women's singles quarter-final, American Amanda Sobhy defeated fourth seed Nouran Gohar of Egypt.
Boston-based Sobhy, the US number one, beat the 19-year-old to avenge her defeat to Gohar in the final of August’s Hong Kong Open.
The Egyptian began well, taking the first game 7-11, before Sobhy, cheered on by a partisan home crowd, came roaring back to win the next three games 11-6, 11-7, 11-4 securing her semi-final position.