Coach Larry Brown let his team rest Tuesday as it prepared for the quarterfinals. With undefeated Spain up next, the Americans might need the time off.

They became the first U.S. men's basketball team to finish anywhere other than first place in the opening round of an Olympics. It won't get any easier against the Spaniards on Thursday.

"They're the best team I've seen thus far," Brown said. Pau Gasol "is as good of a player as there is in the tournament, but they're a veteran team, they're a team that beat the United States at home in Indianapolis at the 2002 World Championships.

"The fact they have gone through their pool undefeated tells you how good they are."

The difference between winning and losing will be huge. A victory would put the United States in the semifinals against Greece or Argentina; a loss would drop it into a game for seventh place against the loser of the Lithuania-China matchup.

And no, they don't give medals for seventh place.

Spain has played its best in the fourth quarters of each game in Athens.

After routing China by 25 points in its opener, Spain outscored Argentina 29-16 in the fourth quarter to win by 11, closed with an 18-8 run to defeat Italy by eight, then outscored Serbia and Montenegro 25-16 in the fourth quarter to win 76-68.

The key factor each time was defense, and when Spain plays defense things can get a little rough. Perhaps that message will be delivered with a shot across Tim Duncan's nose or an elbow to Carlos Boozer's gut.

"Spain is a real rugged, tough team with great size, great experience at the guard positions, and they're a real rough and tumble group," U.S. assistant coach Gregg Popovich said. "They play very physical."

And they get away with it, too. Spain finished the preliminary round with fewer fouls, 84, than any other team.

Spain also had the best free throw percentage, 71.9, while the U.S. team was next to last at 64.4 percent. The Americans' biggest advantage could be offensive rebounding. They lead the tournament with 80, almost twice as many as Spain's 41.

New Zealand's strategy against the Spanards on Monday was to dare them to fire away from beyond the three-point line. Coming into that game, Spain was ranked ahead of only one team, the United States, in three-point accuracy. But New Zealand's strategy backfired when Spain shot 14 for 26 on threes in an 88-84 victory.

"I think any team going against Spain has probably got to be considered an underdog," New Zealand Coach Tab Baldwin said.

Two of the key matchups will be Duncan vs. Gasol and Stephon Marbury vs. Juan Carlos Navarro.

Duncan is shooting 63 percent and averaging team highs of 15.6 points and 11.0 rebounds, while Gasol is shooting 56 percent and averaging 18.2 points and 7.6 rebounds.

The point guard matchup could be a mismatch despite Marbury's advantages in salary, hype and tattoos. He has struggled in each of the Americans' games, getting badly outplayed by Puerto Rico's Carlos Arroyo and Lithuania's Sarunas Jasikevicius in the U.S. team's two losses.

Marbury is shooting only 6 for 30 from the field and 2 for 16 from three-point range, struggling to buy into Brown's preference for a point guard to be the initiator of the offense rather than a scorer. It took Chauncey Billups of the Detroit Pistons an entire NBA season to adapt to Brown's way, but he had 82 games to adjust while Marbury has had only 11.

Navarro is not a traditional point guard, either, but more of a combo guard -- as is his back-court mate, Jose Manuel Calderon. Navarro has been struggling, too, shooting 33 percent overall and 20 percent on three-pointers.

The other quarterfinal pits Italy against Puerto Rico. The semifinals are Friday and the gold medal game is Saturday, meaning the team that stands atop the medal podium in the wee hours Sunday morning will have defeated three tough teams in three days.

It will be a tricky task for anyone, especially for an American team lacking in cohesion, international experience, outside shooting and free throw accuracy.

Pau Gasol of Spain is averaging 18.2 points and 7.6 rebounds in Athens. Spain is "the best team I've seen thus far," U.S. Coach Larry Brown said.