ATHENS (AP) -- The balls are the same as those of the U.S. Open, the surface is like in Toronto, or maybe Indians Wells, and the quality of competition is similar to a Grand Slam.

But compare all you want, in reality the Olympics are a whole different ball game, says Wimbledon champion and top seed Roger Federer.

Gone is the safe nest provided by a familiar entourage, the cushy luxury accommodation and the right to solely look out for No. 1.

"It's impressive. You can't compare this to Cincinnati or any other ATP tournament, or anything else for that matter," says the 23-year old Swiss flag-bearer.

"I'm staying in the village here. I'm not in the same environment, I don't have the same entourage. You see all of the other athletes, how they train, where they are staying. And that's why I like it. It changes so much from the Tour."

Federer is living in the athletes' village, a welcome break from the yawning isolation of the five-star hotel.

"Staying in the village in Sydney was the best thing, so I'm staying in the village here, too," the two-time Wimbledon champion said eagerly. "The atmosphere is great.

"The team spirit is also different here. It's great to be representing Switzerland, something I can usually only do during the Davis Cup. And I will get to play doubles with my friend Yves Allegro -- something else that doesn't happen very often."

Cheerful memories from Sydney could be partly responsible for the rosy glow wreathing Federer's Athens experience.

Four years ago, long before reaching the No. 1 position and winning his three Grand Slam titles, Federer only narrowly missed out on an Olympics medal and gained a girlfriend, former WTA player Miroslava Vavrinec.

Germany's Tommy Haas defeated him for a place in the final and the Swiss subsequently lost the bronze medal match against France's Arnaud Di Pasquale. Though irritating, the result marked the beginning of Federer's ascent.

"I'm hoping to do even better than Sydney," Federer said. "But that's easily said. It was an exploit to finish fourth there. Now everyone expects more from me.

"I'd be happy to get a medal. That's my first objective. The rounds are difficult here. There are a lot of great players and the Olympics represent a lot. If you miss your opportunity you have to wait another four years."

To seize his chance, Federer will need to overcome a tough field, which includes the likes of U.S. Open champion Andy Roddick, No. 4 Carlos Moya, three-time French Open champion Gustavo Kuerten and 2000 U.S. Open champion Marat Safin.

Federer will launch his campaign against Russian Nikolay Davydenko in the first round and could run into Moya, Kuerten and No. 6 David Nalbandian -- who owns a 6-3 career edge against the Swiss -- on way to the final.

Eventually, Federer could face main rival Roddick in the gold medal showdown.

Federer beat Roddick in last month's Wimbledon final and this month's Canada Masters final, increasing his career edge over the American to 7-1 so the American will be bent on retaliation.

"If that comes to fruition, that would be great, but it's not even on my mind right now," Roddick said.

Federer and the others will not only need to overcome a tough field but also the particularly gruelling conditions in the Greek capital, with sizzling court surfaces reaching up to 35 C and stiff winds expected to sweep across court.

"It's really so hot. You really feel it in your feet," Federer said.

Despite the thrilling unfamiliarity of it all, Federer could not help but cling to whatever comforting reference points he could.

"The court is pretty much the same as Toronto or Indian Wells, so that's good for me," said Federer, who won both those tournaments this season.

The tennis starts Sunday.