Carmelo Anthony and Kevin Love scored 16 points apiece to lead the United States to a 110-63 victory.
Kevin Durant added 13 and Anthony Davis had 12 for the Americans, who will face Nigeria on Thursday night.
Anthony, Love, Deron Williams, Russell Westbrook, and Andre Iguodala opened the third quarter with a 21-3 run, turning a surprisingly close 13-point lead into a 67-36 bulge before any of the more celebrated starters finally got to play in the second half.
The nation's first Olympics appearance in women's soccer came to an end for Colombia and University of Toledo's Natalia Gaitan.
Colombia, which failed to score a goal in three matches, fell to France, 1-0. It needed to beat the French by several goals to have any chance of reaching the quarterfinals as one of the two-best third-place teams. Colombia had lost 2-0 to North Korea and 3-0 to two-time defending Olympic champion United States.
Gaitan, a UT captain and a two-time All-Great Lakes region honoree, is expected to join her college teammates in the next several days. The Rockets, who began preseason practice Tuesday, return 18 letterwinners from a team that won their second straight Mid-American Conference regular season championship.
The U.S. clinched first place in its group in women's soccer with a 1-0 win over North Korea.
Abby Wambach scored in the 25th minute for her 141st international goal and third of the tournament.
Host Britain also is perfect through three matches, blanking Brazil 1-0 at Wembley Stadium. Kelly Smith had the only goal. New Zealand beat Cameroon 3-1, and France topped Colombia 1-0. Japan played a scoreless draw against South Africa, while Sweden and Canada tied 2-2.
Zara Phillips gave the royal family plenty to cheer about, helping team Britain to a second-place equestrian finish behind Germany. Princes William and Harry and William's wife, Kate, were in the stands to watch their cousin as she competed in the show jumping final portion of Olympic eventing.
Clay Stanley scored 16 points and the U.S. men's team improved to 2-0 in preliminary pool play with a three-set victory over Germany.
Matt Anderson added 15 points in the 25-23, 25-16, 25-20 win for the defending Olympic champions. The Germans were led by Georg Grozer with 12. Serbia, Bulgaria, and Italy each won in four sets.
Carlos Suarez was upset with the scoring after he dropped a 16-6 decision to Turkey's Ferhat Pehlivan.
Five ringside judges decided the awkward Pehlivan -- who probably slipped and fell to the canvas more than a dozen times during the bout -- landed more scoring punches. Suarez, who is from Lima but is fighting for his mother's homeland of Trinidad and Tobago, called it "a horrible decision."
Daniyar Yeleussinov of Kazakhstan ended U.S. Marine Sgt. Jamel Herring's Olympic boxing aspirations with a 19-9 victory.
In a reversal of their Olympic bout four years ago, Kim Jae-bum of South Korea defeated Ole Bischof of Germany to win the gold medal in the 81-kilogram event.
American Travis Stevens fought several grueling matches to make it to the semifinals, where he lost to Bischof. By that fight's end, Stevens had several bandages wrapped around his head. He lost in the repechage bronze-medal match to Antoine Valois-Fortier of Canada.
Chen Ruolin and Wang Hao led China to its third diving gold in London, this one off the big tower in women's 10-meter synchronized diving. China won going away with 368.40 points, and the country is nearly halfway to its goal of sweeping the eight diving events.
Alan Campbell of Britain qualified fastest for the semifinals of the men's single sculls, providing another boost for the host nation at the Olympic regatta.
Campbell crossed in 6 minutes, 52.10 seconds in the first quarterfinal to beat the times of fellow winners Mahe Drysdale of New Zealand, Lassi Karonen of Sweden and Ondrej Synek, the pre-regatta favorite from the Czech Republic.
Defending Olympic champion France moved to the top of Group A in men's handball after a 32-20 win over Argentina.