The 29-year-old Yorkshireman tonight faces a tricky quarter-final against Simon Rosner in the US Open at Philadelphia’s Drexel University.
The No 2 seed has enjoyed relatively comfortable progress so far, not dropping a game in victories over Harrogate-based Chris Simpson and Egypt’s Karim Abdel Gawad ahead of Wednesday night’s last eight encounter with Germany’s world No 12 Rosner.
While many will already have one eye on the World Open which starts in Manchester on October, Willstrop is intent on doing the increasingly prestigious US Open justice on the East Coast.
According to the former world No 1, the current tournament has gradually become one of the most important on the squash calendar and one he is desperate to succeed in and go one better than the runners-up spot he enjoyed against fellow Yorkshireman Nick Matthew back in 2007.
“It is important for the sport to continue to grow over here,” said Willstrop.
“It really is growing very quickly here, especially so on the east coast. US Squash are a really professional governing body who are putting big efforts in here. There is a good buzz here in Philly.
“It (US Open) has become a huge event in its own right. In terms of the Worlds, I’m happy to have the match competition before that. There are seven or eight days after this to get ready for Manchester. They are two massive events.
“This is a really excellent event. The US events are all fantastic. Philadelphia is an exciting city and the venue and the organisation here make this one of the best - I really enjoy this one.”
Rosner made it through to the last eight only after a serious test of his credentials by Egypt’s Tarek Momen, eventually booking a place in the next round after just over an hour’s squash, triumphing 11-7, 10-12, 11-2, 11-9.
Willstrop, a semi-finalist in the recent NetSuite Open in SanFrancisco, holds the upper hand over his opponent so far, winning all three previous meetings between the two, the most recent being 3-1 triumph in the second round of the British Open in Hull earlier this year.
But the 26-year-old, from Wirzburg, has been steadily knocking on the doors of the world’s top 10 now and Willstrop knows he will have to be on his game in order to progress to the last four.
“We have had tough games before,” added Willstrop.
“He is at that stage where he is really threatening the very top few and he’s improving quickly. He is a big attacker and likes to play fast.”
With a potential semi-final meeting against Matthew at stake, Willstrop will be particularly keen to progress further and take a decent result into the World Open where he will be looking forward to playing in front of a home crowd.
After a straight games win over New Zealand qualifier Campbell Grayson, Matthew is due on court after Willstrop tonight when he will face fellow Englishman Peter Barker.
Seeded three, Matthew will go into the tie favourite over the sixth seed from London, having won 18 of their previous 20 meetings - although Barker won the last encounter between the two when prevailing in the semi-finals of the Canary Wharf Classic in March.
The line-up for the other men’s semi-final was determined on Tuesday night when Karim Darwish and top seed Gregory Gaultier enjoyed straight-game wins over Mohamed El Shorbagy and Mathieu Castagnet respectively.
In the women’s draw, defending champion Nicol David reached the last four following a straightforward 11-6, 11-6, 11-4 over Ireland’s Madeleine Perry and will face fifth seed Joelle King, from New Zealand, who beat England’s Alison Waters 12-10, 11-2, 11-3.
Second seed Laura Massaro faces Kasey Brown - second round victor over Harrogate’s Jenny Duncalf - in the two other women’s quarter-finals on Wednesday night, with Malaysia’s Low Wee Wern and Egypt’s Raneem El Weleily, seeded three, contest the other last eight match.
Tuesday night’s results at US Open, Drexel University, Philadelphia.
 Gregory Gaultier (FRA) bt Mathieu Castagnet (FRA) 13-11, 11-8, 11-6 (47m)
 Karim Darwish (EGY) bt  Mohamed Elshorbagy (EGY) 11-9, 11-9, 11-6 (42m)
 Nicol David (MAS) bt  Madeline Perry (IRL) 11-6, 11-6, 11-4 (34m)
 Joelle King (NZL) bt  Alison Waters (ENG) 12-10, 11-2, 11-3 (37m)