The U.S. Open reached its halfway point on Sunday after a week dominated by Andy Roddick's serve, Andre Agassi's age-defying brilliance, a few Olympics hangovers and, of course, Serena's wardrobe.

However, after the usual jostling for position amongst the top seeds, the serious business is about to begin with most of the ingredients in place for a tasty second week.

Agassi, the oldest man in the draw, is sharpening his game ominously for a shot at his third U.S. Open title, although a quarter-final meeting with world number one Roger Federer is looming large on the horizon.

If the 34-year-old beats close friend Sargis Sargsian in the fourth round and the imperious Federer sees off Andrei Pavel the tournament should witness a classic.

"It's still a match away from it but it would be nice to play him here, at the Open, to get my revenge because he got me badly the last time," said top seed Federer, who was thrashed by the American in the fourth round in 2001.

Federer, who must beat Pavel to reach the last eight for the first time, is seeking to become the first man to win three Grand Slam titles in the same year since Mats Wilander in 1988.

Those awaiting the first heavyweight clash in the women's draw do not have long to wait with two former winners, Lindsay Davenport and Venus Williams set to slug it out in round four on Arthur Ashe on Monday.

The two Americans have met 24 times, with honours even. Davenport, the fifth seed, is the form player with 20 consecutive victories.

Venus, who finished outside the top 10 last year for the first time since 1997, has struggled with injuries and motivation this year, but is sure to raise her game.

"I feel the best I've felt all year," she said after beating Chanda Rubin on Saturday. "I'm ready."

HEWITT LOOMS

Roddick blazed through the opening three rounds, firing down bullet-like serves and thunderous groundstrokes to lose just 18 games on his way to the last 16.

With two of the potential dangers in his quarter, 2000 champion Marat Safin and the man he beat in last year's final, Spain's Juan Carlos Ferrero, falling early his chances of defending his title look bright.

Fourth seed Lleyton Hewitt could put a spanner in the works, however.

The Australian, who blitzed Spain's Feliciano Lopez in straight sets on Sunday night, seems to have rediscovered his zest and would be a tough semi-final hurdle.

Home hopes will rest heavily on Roddick and Agassi, especially with the poor performance of their other men's representatives, including Olympic silver-medallist Mardy Fish.

Fish, who was beaten by Czech qualifier Michal Tabara, joined Taylor Dent and Vince Spadea on a long list of failures while veteran Todd Martin retired after his first round defeat.

With only two American's in the men's third round it was their worst performance in the tournament's history.

Serena Williams, whose raunchy outfits and knee-length warm-up boots have been one of the talking points so far, proved she can let her tennis do the talking.

After looking a little rusty in the opening rounds she cracked down 12 aces against Swiss Patty Schynder and looks in the mood for reclaiming the title she won in 1999 and 2002.

Her match-up with Jennifer Capriati promises to be a real slug-fest.

It's the third straight Grand-Slam quarter-final meeting between the two this year and their 17th clash overall. Williams leads the series 10-6.

"I will just go back and do the same things I've been doing, change nothing and hopefully play a good match," Capriati said.

HENIN FIGHTING

Reigning champion Justine Henin-Hardenne may not have prime time appeal in the U.S., but the businesslike Belgian will not surrender her title meekly.

She looked far from her best in the first week, admitting her gold medal run in Athens had left her tired after the virus that plagued her year, but she is still there fighting.

The same cannot be said of Maria Sharapova, the 17-year-old Wimbledon champion who arrived in a blaze of publicity.

She was humbled in the third round by a resurgent Mary Pierce in one of the performances of the first week.

Other contenders for that award are diminutive Belgian Olivier Rochus who won a five-set thriller against third seed Carlos Moya and Sargis Sargsian who won two marathon matches to reach the fourth round for the first time.

The tide of Russian women sweeping the game gathered pace, with a few new names in the pot, including 17-year-old qualifier Anna Chakvetadze who put stunned French Open champion Anastasia Myskina in the second round.