Hoston: Struck down with food poisoning and unable to last out the first game, top seed Julian Illingworth was forced to hand victory to Lewis Walters in the quarter-finals of the Houston Open at Life Time Fitness in Houston.

With match completed at 10-10 (ret.), the Englishman becomes the only unseeded player in the semi-finals of the PSA World Tour Challenger 10 tournament - the seventh event of the year in the new US Pro Squash Series.

"Semi finals of the Houston Open tomorrow," tweeted Walters. "However not the way I would have liked to get there. I wish Julian a speedy recovery," added the 25-year-old from Nottingham.

Walters will meet Campbell Grayson, the third seed from New Zealand, who beat Joe Chapman of the British Virgin Islands 11-6, 11-2, 11-3.

The other semi-final will pitch fourth-seeded Mexican Cesar Salazar against England's No2 seed Joe Lee.

Cesar recorded his third successive Tour victory over his twin brother Arturo Salazar, winning 11-5, 12-10, 11-8 in 40 minutes.

"Match of the day was the last between Lee and qualifier Syed Hamzah Shah Bukhari," said Life Time squash Tour Director Andre Maur. "Joe took a convincing 2/0 lead but let the third slip away to make it 2/1. The fourth he was back on track and he won 11-8."

RESULTS: PSA Challenger 10 Houston Open, Houston, USA

Quarter-finals:

Lewis Walters (ENG) bt [1] Julian Illingworth (USA) 10-10 ret.

[3] Campbell Grayson (NZL) bt Joe Chapman (IVB) 11-6, 11-2, 11-3

[4] Cesar Salazar (MEX) bt Arturo Salazar (MEX) 11-5, 12-10, 11-8 (40m)

[2] Joe Lee (ENG) bt [Q] Syed Hamzah Shah Bukhari (PAK) 11-6, 11-4, 8-11, 11-8