David appeared on course to claim a straightforward victory in this PSA World Series event at Cathedral Hall as the Malaysian star earned the opening two games of the match.

El Hammamy proved undeterred, though, as she hit back to level the tie, leaving the two players to play out a decider.

The 17-year-old ultimately emerged victorious, claiming a 8-11, 8-11, 11-4, 11-3, 11-9 win over former world number one David after nearly an hour played.

"It was such a good match against a legend like Nicol," said El Hammamy.

"I can’t believe it, I was 2-0 down and I tried to stay positive and not let myself get down.

"I just wanted to focus and play as well as I could.

"I was telling myself that I’m playing against a legend, I’m 2-0 down and I haven’t played my best, so I thought ‘let’s go and keep your mind positive’.

"It’s my first win over somebody in the top ten and it’s not just anyone in the top ten, it’s Nicol and it’s an amazing feeling."

El Hammamy’s reward for her surprise win will be a second round clash against England’s Alison Waters, who beat Hong Kong’s Joey Chan 11-5, 11-7, 8-11, 4-11, 11-4.

Reigning world champion Raneem El Welily enjoyed a straightforward start to her title defence, brushing aside Belgian qualifier Tinne Gilis 11-6, 11-6, 11-6.

The Egyptian star is now due to meet England’s Emily Whitlock in the second round, after her 11-6, 11-9, 11-8 win over France’s Coline Aumard.

Top seed Mohamed ElShorbagy was a comfortable winner in the first round of men’s draw, the Egyptian overcoming England’s Declan James.

ElShorbagy emerged a 11-5, 11-7, 11-7 winner to begin her pursuit of a second Windy City Open title in three years in fine fashion.

France’s Mathieu Castagnet is set to provide the opposition in the second round following his narrow 13-15, 5-11, 11-8, 11-7, 11-9 success against Qatar’s Abdulla Mohd Al Tamimi.

The second round is set to begin tomorrow.