SAITAMA, Japan - International stars have begun preparing for the World Basketball Championship quarter-finals while wondering if any team can stop an American juggernaut from rolling to a title.

An unbeaten US collection of National Basketball Association stars led by LeBron James, Carmelo Anthony and Dwyane Wade has routed foes by an average of 28 points a game, rarely facing a sustained challenge from global rivals.

"They are very talented, gifted and athletic. If they play together, as a block, they will be tough to beat," said Argentina's Emanuel Ginobili, an NBA star with the

San Antonio Spurs.

"For us to play them, it would have to be in the final. If we make it there to see them, we're going to be very happy."

Quarter-final games begin Tuesday with Argentina playing Turkey and Lithuania facing Spain, led by NBA

Memphis Grizzlies star center Pau Gasol.

"We've been very successful but it doesn't matter," Gasol said. "From now on we just have to win every game and they're all going to be tough."

The Americans will try to advance on Wednesday against Germany, powered by star NBA forward Dirk Nowitzki, with the winner to face European champion Greece or France in Friday's semi-finals.

"They have one of the premier scorers, one of the best players, in our league in Dirk," James said. "Weve got to do a great job in trying to contain him and try to make sure we contain some of the others."

Nowitzki sparked the

Dallas Mavericks into the

NBA Finals, where they lost to Miami. But the power forward has proven he can cope with the responsibility.

"Dirk knows exactly how to handle pressure. He does it every night. He led Dallas to the NBA Finals. There's more pressure there than here," said German captain Ademola Okulaja.

"It's going to be exciting to play the US team. They are great players. We will see if all those guys come together and play well at the same time. Who knows, if we catch a good day..."

Ronny Turiaf, a French forward from the NBA

Los Angeles Lakers, warned that even on their best day some teams will struggle to challenge a versatile US squad that dominates with defense.

"That will be a hard team to beat, the best young players in the NBA," said Turiaf. "It's going to be really tough to get them. They made a good adjustment to the international game. It's tough for anybody to match up with them."

Australia coach Brian Goorjian knows that all too well after the Boomers were bounced 113-73 in a round-of-16 game.

"I think they have a very good chance of winning that gold medal," Goorjian said. "They come after you for 40 minutes. They havent lost a game yet and they are getting better as they go along.

"I just dont know if anyone can physically play like that for 40 minutes."

France is sparked by NBA standout Boris Diaw of the

Phoenix Suns but it was when San Antonio star guard Tony Parker suffered a broken finger on the eve of the event that the French team came together.

"We could cry and say, 'Oh no, it's over.' But we didn't do that," Turiaf said. "Tony's loss has let us realize we are a team. It's time for other guys to step up."

The Greeks have been winning with a team emphasis for years.

"We showed one more time that we are 12 players that play like a team," said veteran Vasilis Spanoulis.

Turkey has no NBA greats but a team bond that could threaten Argentina.

"Argentina has much more experience than we do," said Turkish top scorer Serkan Erdogan. "At this level, a team like Argentina will not feel the pressure. We feel no pressure either. We will just play our game."

Stopping NBA talent like Ginobili, Andres Nocioni, Carlos Delfino and Fabricio Oberto will be tough for the Turks just as shutting down Gasol will be Lithuania's biggest challenge.

"Everyone knows that Gasol is a great player. It's going to be a tough game. Spain has played impressively," Lithuania guard Linas Kleiza said.