BEIJING, CHINA - Michael Phelps swam into Olympic history on Sunday but his staggering achievement failed to inspire his country?s vaunted track sprinters who came off second-best to the high-flying Jamaicans in the women?s 100m final.

The 23-year-old Phelps won an historic eighth gold medal, surging past yet another Olympic milestone as the United States clinched the men?s 4x100m medley relay in world record time.

With the victory, Phelps overtook compatriot Mark Spitz, whose seven swimming golds at Munich in 1972 were the most at a single Games.

The US squad of Aaron Peirsol, Brendan Hansen, Phelps and Jason Lezak won a tight relay in 3:29.34, Lezak holding off Australian individual world record-holder Eamon Sullivan on the closing freestyle leg.

?I don?t know what to feel right now, there are so many emotions going through my head and so much excitement,? said Phelps.

?This is all a dream come true, just to be able to imagine anything, to go through the ups and downs and accomplish everything you ever dreamed of.?

On the last day of the pool programme, Germany?s Britta Steffen won the women?s 50m freestyle, edging US veteran Dara Torres to complete a sprint double while the US also had to settle for silver behind the Australians in the 4x100m medley relay.

Later Sunday, America?s crack women?s sprinters flopped in the 100m final.

Shelly-Ann Fraser led an unprecedented Jamaican sweep with the result coming just one night after compatriot Usain Bolt won the men?s 100m in a world-record 9.69secs.

Fraser powered to victory with Sherone Simpson and Kerron Stewart sharing second.

America?s best finisher was Athens Olympic runner-up, and 2005 world champion, Lauryn Williams who was fourth, US champion Muna Lee was fifth and 2003 world champion Torri Edwards last.

?It?s heartbreaking,? Lee said.

By the end of the day?s programme, the busiest of the Games with 37 finals, China still led the medals table with 35 golds out of a total of 61; the US were in second spot with 19 golds out of 65.

America?s second gold of the day?s three came from Serena and Venus Williams who won their second tennis doubles title to add to their 2000 triumph with a 6-2, 6-0 victory against Anabel Medina Garrigues and Virginia Ruano Pascual of Spain.

?I?m so excited I can?t even speak,? said Venus.

In rowing, the US triumphed in the women?s eights and deprived Romanian Georgeta Andrunache the chance to win a sixth gold and become the most successful rower in Games history.

There was disappointment in the gymnastics where reigning floor exercise world champion Shawn Johnson was pipped for gold by Romania?s Sandra Izbasa.

There were no problems for US women?s basketball team who thrashed New Zealand 96-60 for their fifth win in five games and will now face South Korea in Tuesday?s quarter-finals.