Andre Agassi escaped another first round defeat on Monday and gained a measure of revenge when his opponent Mardy Fish retired at 4-6, 7-6, 4-1 in the Cincinnati Masters in Cincinnati, Ohio.

American Fish, last year's losing finalist, quit in the third set because of a back injury, allowing the former world number one to advance to the second round.

"It's disappointing when a match ends like that," said the 34-year-old Agassi.

"But I was happy with the way I was playing as the match went on, and was hitting through my shots more, which is a good sign for me."

Agassi, who has been struggling to find his form in recent months, was beaten by Fish in an emotional match in the semi-final of the Siebel Open in February.

He lost in the first round of the French Open in May, one of three consecutive opening round defeats, and missed Wimbledon.

It looked as though the eight-times Grand Slam winner was heading for another early exit when unable to convert a break point at 4-3. He then lost his next service game as Fish clinched the first set.

STAMPED AUTHORITY

Agassi stamped his authority in the second set tie-break, using his power and control from the baseline to win 7-3.

The younger American's power disappeared in the third set and he eventually succumbed to the back injury when trailing 1-4.

"I can't imagine that serving 130-mph was healthy for him," said Agassi. "Once his serve fell off in the third set, it was hard not to notice anything (was wrong).

"I started hitting my shots better in the tie-break and started feeling better afterwards. It would be nice to see my game elevate as the tournament goes on now. I'm certainly ready for that."

Spaniard Carlos Moya, another former champion, was also tested.

The world number four was a set and a service break down against British qualifier Arvind Parmar before wriggling out of trouble with some patient baseline work. Moya won 3-6, 7-5, 6-2.

Guillermo Coria of Argentina, meanwhile, pulled out of the tournament with a shoulder injury sustained last week in Toronto.