The Yorkshireman is renowned as a brilliant shot-maker, but he has rarely produced a greater number of inventive strokes or survived as many fast, creative rallies as he did in winning 7-11, 11-6, 11-8, 11-8 against the young Egyptian.
Even more remarkable is that Willstrop came from behind after having endured an indifferent spell of form recently by his excellent standards. He did it by surviving a fiercely punishing early pace in which the first two games lasted only 24 minutes, by pushing up the court to volley, and by unleashing a spate of wrong-footing drives and volleys, coupled 
with treacherously tight, clinging drops.
“I don't know if this is a defining moment,” he said. “I don't know if there is one – it's more series of moments and days and hours which make you what you are. Tonight's win is abut an awful lot of time spent with the people who are close around me.”
For a while it seemed that the outcome would go the same way as the other four encounters, which Ashour has won. The world champion set off at a tremendous pace, launching some fierce drives which often had Willstrop plunging around, and moving rapidly from 4-3 to 8-3, and then from 8-5 to 10-5, finishing with a hustling cross court drive which forced Willstrop to snatch his volley and put it into the tin.
But from 3-3 in the second game Willstrop began to score more often with tight drops at the front, and then to cope better with the pace, dictating it more himself, and gradually becoming inspired as he moved into the lead.
One volley drop sequence which ended with a neat winner by him got the crowd noisily involved, and that further increased Willstrop's adrenalin and lifted his confidence.
A backhand fast trickle drop, hurrying the ball round the top right corner, got him to one game all, and when he came from 2-5 to 8-5 with a run of wonderful rallies in the third game, pushing Ashour short and then dragging him long repeatedly, it became evident that he could win.
Ashour, often playing superbly himself, got back to 7-8, at which stage Willstrop produced a fast boast winner – rocketing the ball off the side wall from a deep position - another fast trickle at the front, and a cut-off volley drop, all three of which went for winners.
That put him two games to one up, and soon he was making impressive progress in the fourth game as well, reaching 3-0, then 4-1, and then going from 5-2 to 8-2, all with winners in rallies which had the spectators shouting themselves hoarse.
Much of the time Ashour had been too much on the defensive, but now he made a brave and intelligent push, taking over the attacking role, and coming from 5-9 to 8-9. It was then that Willstrop showed his gritty qualities, hanging on and retrieving hard, and coaxing just enough errors out of his opponent to get across the finish line.
Willstrop did once beat another famous Egyptian, Amr Shabana, in the world team finals to help England clinch the title, but that was four years ago, and one suspects the standard of all these players has risen since then. Whether this is now a bit of a breakthrough for Willstrop will be interesting to see.