England’s top seed James Willstrop returned to the top of the PSA world rankings for March after reaching the semi-finals of the Davenport North American Open in Richmond, Virginia, which will feature the event’s top four seeds.

Willstrop’s opponent, Egypt’s Amr Shabana was forced to concede the match early in the second game because of a knee injury.

By reaching the last four, Willstrop earned enough ranking points to regain the world number one position from his great English rival, Nick Matthew, the world champion from Sheffield.

Willstrop, who topped the rankings for the first time in his career after three major event wins in Hong Kong, Kuwait and India at the end of 2011, said: “It’s great news to be back on top but I would find it very difficult to celebrate because nobody wants to win a match that way.”

Willstrop meets French ace Gregory Gaultier in the semi-finals, a re-run of the 2008 final which Willstrop won. Gaultier overcame young Egyptian qualifier Karim Abdel Gawad, winning 11-6, 11-2, 11-6 in 39 minutes.

Afterwards he said: “I am feeling good this week. When you are well looked after, and feeling relaxed, and nothing is going on to upset your brain, then you can play well.”

In the other semi-final, Matthew meets Ramy Ashour in a re-run of the last three NAO finals. Ashour won in 2009 but Matthew has won the last two events and is hunting down a hat-trick of titles this year.

Ashour confirmed his return to peak fitness with a devastating victory over fellow Egyptian Karim Darwish. After the first two games were shared, Ashour wore down his opponent and powered through the third and fourth, making Darwish look demoralised at the end.

Ashour said: “It’s never easy to beat Karim. We had breakfast together aand spent a lot of time together during the day, but as soon as reached the court we know that we have a job to do and try to be as professional as possible.”

Matthew, who had struggled to hit top form in the first two rounds, beat battling German Simon Rosner in four hard games.

Matthew dominated the opening two games and seemed set to wrap things up quickly as he led 8-4 in the third, but Rosner recovered to win a succession of breathtaking rallies.

He won the game 11-9 but the effort clearly took its toll as Matthew stayed in front throughout the fourth.

Matthew said: “I started well in those first two games but I need to step up another notch against Ramy. He is playing very well this week. It will be strange playing him in the semis after meeting him in the past three finals.”

Davenport North American Open, presented by Brown’s Jaguar

Quarter-finals:

(1) James Willstrop (Eng) bt (6) Amr Shabana (Egy) 11-5, 2-0 retired (12m)
(3) Gregory Gaultier (Fra) bt Karim Abdel Gawad (Egy) 11-6, 11-2, 11-9 (39m)
(4) Ramy Ashour (Egy) bt (5) Karim Darwish (Egy) 12-10, 8-11, 11-5, 11-3 (56m)
(2) Nick Matthew (Eng) bt Simon Rosner (Ger) 11-7, 11-6, 9-11, 11-6 (63m)