Andre Agassi continued his good run at the Master Series in Cincinnati to set up a dream semi-final against U.S Open champion Andy Roddick on Friday.

The 34-year-old 11th seed emerged from a battle of former world number ones with a 7-6, 6-3 victory over Spain's Carlos Moya, saving six set points in the first set.

The crowd favourite saved the set points in an epic tiebreak in which Moya went toe-to-toe with the four time Grand Slam winner until Agassi's varied ground strokes induced the fourth seed to over-hit when trailing 13-12.

"That tiebreak was definitely one for the memories -- I don't remember playing one that deep before," Agassi said.

"To come out two days in a row and start raising the standard is what creates belief.

"It's important to me beat some of the best in the world and get the belief in my game," added Agassi who has been suffering from a lengthy hip injury and repeatedly the subject of retirement speculation.

However, Agassi struck the ball with conviction against an opponent who possessed superior mobility and a fiercer forehand but was narrowly outsmarted by the tactical skill and technical variety of one of the game's all-time greats.

The victory created a confrontation of two generations of leading Americans.

Roddick, the 22-year-old defending champion joined Agassi in the semis after a 6-3, 6-3 win over Tommy Haas, the former world number two from Germany.

Roddick rarely needed to rely on his record-breaking serve and will be favoured to beat Agassi, despite having managed it only once in five attempts.

IMPRESSIVE HEWITT

Earlier, Lleyton Hewitt continued his build up for this month's U.S. Open by winning another battle of former world number ones with a 6-4, 6-4 victory over Marat Safin.

The Australian 10th seed beat the 24-year-old Russian in a contest containing plenty of brilliant counter-hitting and a little controversy to set up a last-four meeting with Spain's Tommy Robredo.

"I played pretty well on his service games," said Hewitt, the 2001 U.S. Open winner.

"I feel like I have been playing pretty well this year... I feel that I am near the mark. I just hope that in a few weeks time I will get the breakthrough."

Robredo followed up his conquests over former world number one Juan Carlos Ferrero and Briton Greg Rusedski by easing past Frenchman Fabrice Santoro 6-2, 6-3.