The United States sailed past South Korea 80-57 Wednesday to lead three unbeaten teams at the Athens Olympics women's basketball tournament.

Lisa Leslie scored 25 points in 23 minutes to lead the Americans to their third straight win in preliminary group B.

The South Koreans made it close early, but the United States pulled away with a 25-2 run connecting the second and third quarter for a 58-34 lead.

"We had a slow start, but we improved our defense and won this game," said American guard Diana Taurasi. "The coach told us to play hard defense and not allow open shots at the half break."

Rotating their players frequently, the reigning Olympic and world champion had no difficulty holding their comfortable lead to the end.

"The young players had pretty good chemistry in the court, that' s why they stayed in the game for a long time," said the American coach Van Chancellor.

Tina Thompson added 18 points for the United States.

The United States will clash with Spain, who also improved to 3-0 with Wednesday's 91-57 rout of New Zealand, on Friday to vie for the lone lead in Group B.

Australia was the other unbeaten team after three rounds of preliminaries. After blasting Asian runner-up Japan 97-78, the Sydney Olympic silver medallist led Group A with three wins against no loss.

Also on Wednesday, Russia beat Brazil 77-67 to hand the latter its first defeat at the 12-team tournament. Russia and Brazil both had a 2-1 record while the South Americans placed second due to points won-loss ratio.

Greece finally recorded its first victory on home soil by beating Nigeria 83-68 in a group A match. Czech Republic also ended its two-game losing streak with a 98-83 victory over Asian champion China.

Nigeria and South Korea remained as the only teams without a win.

Twelve teams are competing in two groups in the preliminaries of the Olympic tournament with top four finishers from each group to gain berths in the quarter-finals.