Maybe all that talk from Andy Roddick and Venus Williams about taking the Olympics as seriously as a Grand Slam was just that: talk.

Or perhaps they just played poorly against inspired opponents.

Either way, both former No. 1 players were sent home by straight-sets upsets in the third round Wednesday, taking their star power with them and leaving the tournament with the feel of just another second-tier event.

A day after top-ranked Roger Federer lost, apparently easing Roddick's path to a medal, the U.S. Open champion was beaten, 6-4, 6-4, by No. 16 Fernando Gonzalez of Chile.

A short while later, 2000 gold medalist Williams lost to Mary Pierce of France by the same score.

"With each player, it's personal, how big it is. Some guys really don't care that much. I cared a lot," Roddick said. "It's not the biggest thing in our sport, but it's the biggest thing in sports."

Late in his match, some spectators chanted, "Chile! Chile!" When a group of Roddick's fans responded with "U-S-A! U-S-A!", they drew boos and whistles from people who must be thrilled by the surprising flop turned in by the American tennis players.

Just 11/2 weeks ago, the U.S. squad appeared stacked, with Roddick, the Williams sisters and Jennifer Capriati all slated to play singles.

But Capriati and Serena Williams pulled out of the Summer Games with injuries after the deadline for replacing them on the roster. Serena informed the U.S. Tennis Association a few hours before the team flew to Greece.

"Venus, right before we got on the plane, she was like, 'I just hope nothing else happens,' " U.S. Coach Zina Garrison said. "I'm kind of superstitious in my own right, and I was like, 'Let's talk about it after we get off the plane.' "

Now, for the first time since tennis returned to the Olympics as a medal sport in 1988, no U.S. woman will leave with a singles medal. That's because No. 16 Chanda Rubin lost to No. 2 Amelie Mauresmo of France, 6-3, 6-1, Wednesday, and Lisa Raymond was eliminated by Alicia Molik of Australia, 6-4, 6-4.

As a fitting nightcap, the top-seeded U.S. men's doubles team of Bob and Mike Bryan were knocked off by Gonzalez and Nicolas Massu, 7-5, 6-4.

"Just a pretty rough day for Americans," Garrison said.

Some did stick around, though.

Mardy Fish got past Max Mirnyi of Belarus, 6-3, 4-6, 6-1, and Taylor Dent beat Ivan Ljubicic of Croatia, 6-4, 6-4, to reach the singles quarterfinals. And Martina Navratilova and Raymond advanced in doubles when their opponents, Mauresmo and Pierce, pulled out. Mauresmo developed a rash from a skin allergy during her win over Rubin.

Who would have thought that Navratilova, an Olympic rookie at 47, and a couple of guys yet to fulfill their potential -- Fish and Dent -- would be the team's final medal hopes?

Garrison refused to read too much into the string of disappointments.

"It just means what it means. It's just another day," she said. "We have a big Grand Slam coming up, where Americans always want to do well. I was just trying to keep my girls focused on doing well at the Olympics and not worry about the [U.S.] Open coming up."

Roddick, Federer and Venus Williams will want to regroup quickly before heading to New York for the Aug. 30 start of the year's last major.

"Right now, I'm looking forward," Roddick said. "I've got a pretty big tournament coming up."

But he also did seem genuinely downcast at failing to even come close to a medal at his first Summer Games. Roddick and Fish lost in the first round of doubles; Venus Williams and Rubin did, too.

"I'm gutted right now," said Roddick, broken once in each set by Gonzalez and distracted by a ruling that prompted a running dialogue with the chair umpire.

"It's not every day we get to play this," he added. "You can't say, 'Next year.' "

Williams lost her serve in the last game of each set and double-faulted on match point against Pierce, a two-time major champion who faces No. 1 Justine Henin-Hardenne of Belgium for a berth in the medal round.

Other quarterfinals: Mauresmo vs. No. 5 Svetlana Kuznetsova of Russia, Molik vs. No. 8 Ai Sugiyama of Japan, and No. 11 Francesca Schiavone of Italy vs. No. 3 Anastasia Myskina of Russia.

The men's final eight: Gonzalez vs. No. 8 Sebastien Grosjean of France, Dent vs. Tomas Berdych of the Czech Republic, Fish vs. Mikhail Youzhny of Russia, and No. 3 Carlos Moya of Spain vs. No. 10 Massu.

Berdych, just 18, continued his amazing run by outlasting No. 15 Tommy Robredo of Spain, 7-6 (7-2), 4-6, 8-6, a day after shocking Federer.

"Everybody," Berdych shrugged, "is beatable."

Venus Williams, a gold medalist in 2000, lost her serve in the final game of each set and fell to Mary Pierce of France, 6-4, 6-4."It's not the biggest thing in our sport, but it's the biggest thing in sports," said Andy Roddick, disappointed after his ouster from the Olympic Games. He lost to Chile's Fernando Gonzalez.