Jamaica made a clean sweep of Olympic sprint golds on Thursday with victory in the women's 200 meters, humbling the United States, the traditional track and field superpower.

The Americans had a nightmare night with both the women and the men dropping their batons during the heats of the 4x100 meter relay to crash out. They also lost the final of women's softball, the first time they have failed to win gold in that event.

• Brilliant Bolt seals sprint double | Images

The Caribbean island's Veronica Campbell-Brown powered to gold in the 200m, taking a meter's lead by the halfway mark.

The 2004 winner's face was creased with pain but broke into a broad grin at the finish, where she dropped to her knees for a prayer.

American world champion Allyson Felix came second and 100 meter silver medalist Kerron Stewart of Jamaica was third.

The victory will bring more rejoicing to an island already exultant over the two world records and double sprint gold of Usain "Lightning" Bolt. His jawdropping speed has brought superlatives pouring forth from media and commentators.

Jamaica also won the women's 100 meters.

"The Americans have dominated (in the past), but this Olympics [Images] has been a Jamaican Olympics," said Stewart.

Bolt, 22 on Thursday, collected his second gold in a rain-soaked ceremony in the Bird's Nest stadium and gave his signature lightning bolt gesture for the cameras.

The head of the International Olympic Committee has questioned the Jamaican's sportsmanship, taking exception to his exuberant celebration of his 100 meter win on Saturday when he pounded his chest even before crossing the finish line.

"I think he should show more respect, shake hands, give a tap on the shoulder to the other ones. Not making gestures like the one he made," Jacques Rogge said. "He still has to mature."

Jamaican coach and former sprinter Don Quarrie defended Bolt, saying his celebrations were just youthful high spirits, from a man who is "playful, funny, happy".

LITTLE CONSOLATION

The United States have won a major sprint medal at every Games since 1984 and this year's collection of silvers and bronzes will be little consolation.

The failure in the relays, an unexpected loss in the final of the women's water polo to the Netherlands and defeat to Japan [Images] in the softball will be salt in the wounds for the Americans.

Softball will not be at the 2012 Games and the US had won every gold on offer since it became an Olympic sport in 1996.

There was a win for the US in the men's 400 meters, where LaShawn Merritt beat defending champion Jeremy Wariner to deliver the seventh straight gold in the event for the Americans.

That will do little to chip at the dominance of China in the medals table. The hosts have a commanding 45 golds to the US's 27, a lead that China says shows it now has the sporting prowess to match its growing economic might and superpower clout.

In Athens, the U.S. team topped the medals table with 36 golds to China's 32, but the hosts have invested heavily in selecting and training athletes intensively over many years.

"The world has to learn to live with a change of geopolitical nature," the IOC's Rogge said, adding that China's sporting success would last "as long as their sports system lasts".

Americans did enjoy success in women's beach volleyball.

An excited home crowd sheltered from torrential rain as China's Tian Jia and Wang Jie lost to the defending champions, U.S. pair Misty May-Treanor and Kerri Walsh, in straight sets.

May-Treanor and Walsh, who have dominated the sport for five years, left the door open to a return in London [Images] 2012, but said that might depend on plans to have children.

The rain did not matter to the men's marathon swimmers.

Dutchman Maarten van der Weijden, who was given only a slim chance of survival when diagnosed with leukemia seven years ago, won the 10km swim, one of the most testing Olympic events.

A stem cell transplant and chemotherapy saved van der Weijden's life.

"That makes it extra special," he said. "It proves that even after such an illness you can win gold."

As expected Cuba's Dayron Robles [Images] won the 110 meters hurdles in a race that had been promoted as a showdown with Chinese sporting idol and defending champion Liu Xiang. But Liu hobbled out of his heat with an injured foot, devastating Chinese fans.

HORSE DOPE TESTS

Equestrian sports were embarrassed by positive drug tests on four horses that could lead to Norway's Tony Andre Hansen losing his bronze medal.

Four horses tested positive for capsaicin, a banned chili derivative which is sometimes pasted onto horse's forelegs to "hypersensitive" them so they try harder to lift their smarting shins over fences and avoid incurring penalties.

Hansen, on his horse Camiro, was a member of the Norwegian team that won bronze in Monday's team show jumping competition. A decision on his team's medal will come after a B-sample test.

"It is certainly a serious blow to the sport and we are very well aware of the possible implications it can have," said Sven Holmberg, the chairman of the International Equestrian Federation's jumping committee.