Andre Agassi reached his first quarter-final in five months with a revitalised performance that enabled him to overcome Juan Ignacio Chela 6-3, 6-3 in the Cincinnati Masters Series on Thursday.

A former winner of all four Grand Slam titles built on his improved form of the previous round and struck the ball with more confidence and assertiveness than earlier in the year when he was bothered by a hip problem.

The 34-year-old 11th seed also moved much better than recently, enabling him to dictate the pattern against Chela and to repel for at least another day the continual talk of retirement.

The highlight of the match was the rally that took Agassi to break point on Chela's serve when leading 4-3 in the second set.

He brought his 17th-seeded Argentine opponent forward with a drop shot before rolling a backhand topspin lob to within centimetres of the baseline to make the winner.

The charismatic American then converted the break chance at the first attempt with a passing shot and closed out the match without fuss.

He was delighted with his work.

"Tonight I felt real good. It's the first match in a long time that I felt that comfortable with my game," Agassi said.

"It's a real confidence thing out there.

"You have to believe in what you are doing because the match is decided on just a few points. Finally having a few matches in a row is helping me to feel comfortable out there at last."

Agassi now lines up in a battle of former world number ones against Carlos Moya, who had to fight hard to get past lucky loser Wayne Arthurs.

BREAK DOWN

Moya won 7-6, 3-6, 7-6, but needed to rally from a break down in the deciding set.

The Spaniard also uncharacteristically got a code violation for striking a ball over the grandstand in a fit of temper.

Two other former world number ones meet in the top half of the draw as Marat Safin takes on Lleyton Hewitt.

Safin overcame Ivo Karlovic and a bout of histrionics when he was incensed by a line decision to win 7-6, 6-7, 6-4 against his giant Croatian opponent.

Hewitt had an easier time of it in thrashing Tim Henman 6-1, 6-4 to register his eighth victory over the Briton in as many attempts.

Henman was possibly suffering from fatigue following a second round match that finished in the early hours of Thursday morning, and he could never match the energy, intensity and mobility of the Australian.

Hewitt, whose long-lasting legal wrangle with the ATP started when he was fined for refusing an interview with ESPN before a match here two years ago, looks in good shape to reach the final.

The favourite for the title, however, remains the defending champion Andy Roddick, who raced into the last eight with a 6-2, 6-3 win over Paradorn Srichaphan of Thailand.

Also advancing to the last eight were Spain's Tommy Robredo, Germany's Tommy Haas and France's Fabrice Santoro.

Robredo needed a pair of tiebreaks to edge big-serving Briton Greg Rusedski while Santoro eased to a 6-0, 6-3 victory over Jonas Bjorkman.

Haas was forced to dig deep to record a 6-3, 5-7, 6-4 win over Robin Soderling of Sweden in a night match.