Australian number one David Palmer overcame a badly injured ankle to edge past Tom Richards of England in today's second round of the Viridian Australian Open to reach the quarter-finals of the third PSA World Series squash event of the year in Canberra.

The unseeded former champion hurt his ankle when he fell awkwardly during his first round win over Malaysian Mohd Azlan Iskandar on Monday and needed extensive treatment at the Australian Institute of Sport just to take the court.

The 35-year-old struggled badly during the first game and looked headed for an early exit in possibly his last ever Australian Open.

However, as the match wore on he slowly started to gain more movement and began to dominate an increasingly frustrated Richards.

Palmer, who had never before lost to the 25-year-old Englishman in seven previous meetings, took a close second game - then made decisive breaks in the third and fourth to take the match 4-11, 11-9, 11-6, 11-5 in 65 minutes.

He now has a day off for more treatment before facing third seed Karim Darwish in the quarter-finals following the Egyptian's 11-5, 8-11, 11-5, 11-7 win over Hong Kong's Max Lee.

"I was happy just to get on court," Palmer said. "I've been out at the AIS getting treatment and they've done some great work.

"In the early stages it felt like I was dragging my leg around and I think winning that second game was very important - if Tom had gone two-love up I think he would have run away with it.

"I think it probably affected Tom's game a little bit because it can be hard to play against someone you know has an injury."

England's Nick Matthew remained on track to defend his title with an impressive win over Malaysia's Ong Beng Hee.

The world number one from Sheffield absorbed everything the Malaysian threw at him to close out the match 11-7, 11-8, 11-9 and move into a quarter-final against Laurens Jan Anjema of the Netherlands.

Anjema reached the final eight when he beat American Julian Illingworth 11-4, 11-3, 11-3.

Matthew and Ong have been opponents since their junior days and the Malaysian used all his experience to undo his opponent, hitting an array of shots to all parts of the court.

However, Matthew was up to the challenge despite struggling to close out the match in a tight third game.

"I seem to get to seven, eight and nine points okay before hitting a bit of a roadblock," said the 31-year-old Englishman. "But that's a credit to Beng Hee, he stayed around to fight to the end. He changed his tactics every point so it was hard to feel comfortable.

"I was happy to get off three-love really. I'm getting through, I'm not really playing with full fluency yet, but it's early days in the tournament so hopefully I'll find it.

"Everything's sort of in place, it's just a matter of piecing the bits together - I'll get that in the next few days."

Matthew will need to be at his best against Anjema, who followed up his first round upset of fifth seed Thierry Lincou with a dominant display against Illingworth.

"I played really well tonight - it's tough to follow up a win over someone like Thierry," said the six-time Dutch champion. "You walk around with your head in the clouds but you have to tell yourself it's a new day and there's work to be done."

RESULTS: PSA World Series Viridian Australian Open, Canberra, Australia

2nd round (top half of draw):
[1] Nick Matthew (ENG) bt Ong Beng Hee (MAS) 11-7, 11-8, 11-9 (50m)
Laurens Jan Anjema (NED) bt Julian Illingworth (USA) 11-4, 11-3, 11-3 (32m)
David Palmer (AUS) bt Tom Richards (ENG) 4-11, 11-9, 11-6, 11-5 (65m)
[3] Karim Darwish (EGY) bt [Q] Max Lee (HKG) 11-5, 8-11, 11-5, 11-7 (42m)

Remaining 2nd round matches:
[4] James Willstrop (ENG) v [Q] Alan Clyne (SCO)
[5] Gregory Gaultier (FRA) v Adrian Grant (ENG)
[6] Peter Barker (ENG) v Mohd Nafiizwan Adnan (MAS)
[2] Ramy Ashour (EGY) v Stewart Boswell (AUS)

Official event website: www.australiansquashopen.com