Roger Federer lined up a semi-final with the hottest of the current American hopes, crushing Jose Acasuso 6-4, 6-3 to storm into title contention at the 2.45-million-dollar ATP Cincinnati Masters.
The Swiss world number one showed that his layoff of more than a month after lifting a third straight Wimbledon title had done no harm as he rolled over his outclassed Argentine challenger.
"I feel I'm getting close to my best form," Federer said. "I've been able to groove my game this week. I'm happy with the way it's going."
Federer, bidding for a 31st career trophy and ninth this season, advanced to a Saturday semi-final against resurgent 58th-ranked Robby Ginepri, who upset two-time Grand Slam winner Marat Safin 6-2, 6-3.
At the bottom of the draw, two-time finalist Lleyton Hewitt, finally healthy after a stomach virus last week, extended his bid for a second title this year, beating the third and final Russian in the quarters, Nikolay Davydenko, 6-2, 6-3.
The Australian will play against 2003 US Open winner Andy Roddick, who eliminated Russia's Mikhail Youzhny 2-6, 6-3, 6-4.
Roddick lost his serve in the first game, which temporarily put him on the back foot. But the American quickly recovered.
"When the second set started I didn't put much into the first set because it was just so quick," he said. "It was almost easier to recover from that than it would be like a 7-6 or something like that. I just tried to start with a clean slate."
Roddick, whose only Grand Slam title came at the US Open two years ago, is prepared for a battle against the always combatative Hewitt, against whom he has won only one of seven matches.
"We've had a lot of close matches and I haven't come out on the better end of them, which is a little rare for me," Roddick said.
"I want to get another crack at these guys. The only way that I'm going to beat them is by playing them and putting myself in position enough times."
Ginepri's victory derailed a possible re-run of the Australian Open semi-final of seven months ago, where Safin handed the silky Federer one of only three defeats so far this season.
After a pair of patchy performances this week, Federer is back on his standard lethal form as he uses this week for his only tune-up prior to the August 29 start of the US Open.
The victory was the 62nd of the season for the top seed, who is playing for the first time since lifting a third Wimbledon title.
He has already turned over a losing 1-4 record at Cincinnati with his fourth victory of the week.
COLLATED RESULTS
(x denotes seed):
Quarter-finals: Robby Ginepri (USA) bt Marat Safin (RUS x4) 6-2, 6-3; Roger Federer (SUI x1) bt Jose Acasuso (ARG) 6-4, 6-3; Andy Roddick (USA x5) bt Mikhail Youzhny (RUS) 2-6, 6-3, 6-4; Lleyton Hewitt (AUS x3) bt Nikolay Davydenko (RUS x6) 6-2, 6-3