Top-seeded Willstrop reached the quarter-finals of the British Open at London's O2 Arena late on Wednesday with a tenaciously carved-out 9-11, 11-7, 11-7, 11-5 win over his former England colleague Alister Walker, suggesting he is in a rich vein of form.
But Matthew is the defending champion and even though he is only seeded three here, he may be many people's favourite to triumph again in Sunday's final.
Matthew joined Willstrop in the quarter-finals on Thursday with a hard-fought 11-5, 8-11, 11-4, 11-6 win over another England colleague, Tom Richards.
Willstrop's problem is that although he played brilliantly and held a match point against Matthew in the last British Open final three years ago in Manchester, he has since lost 10 times in a row to his life-long rival on the PSA Tour.
But as the younger man, he believes his chance will soon come.
"Nick was number one for a long time and then, in January, I took over," Willstrop told The Guardian newspaper.
"He beat me in February and got it back and then, in March, I was determined to become number one again."
That happened after the North American Open at Richmond in Virginia, where Willstrop said he had played "a blinder" in the final to beat the brilliant former World Open champion from Egypt, Ramy Ashour, in straight games.
"Nick's game has stifled me at times," Willstrop admitted. "He has had it over me quite substantially. He's won our last 16 or 17 matches. That's a lot. He's been on this run against me because, for two years, he was the best in the world.
"But now I'm number one. And at 31, Nick's at his peak, and I'm 28 and getting better all the time."
Willstrop also denied that the defeats have left psychological baggage.
"None of them have been devastating losses and he was beating everyone else as well," he pointed out.
"I look at my defeats sensibly and realise I've played very well against Nick. I'm ready to beat him again."
Matthew, however, denied there will be extra pressure on him as the titleholder.
"I don't go into this week feeling like a defending champion," he said.
"I feel like one of many with the same possibilities, as one of those who is trying to win the tournament. And I'm still looking to be number one again."
Willstrop has earned a meeting on Friday with Mohamed El Shorbagy, the former world junior champion from Egypt, but has both Ashour and Amr Shabana, the four times former world champion, in his half.
Matthew could progress to a semi-final repeat of November's World Open final with Gregory Gaultier, the former world number one from France.
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