by Robert Smith
ATHENS, Aug 16 (AFP) - It's early days but America's sporting aura of invincibility is under assault at the Athens Olympics.
Two seismic shocks have rocked the Stars and Stripes in the opening days of the Games with Puerto Rico stunning the United States' Dream Team basketballers and the American women shedding their 16-year unbeaten run in the 4x100m freestyle in the pool.
This follows the Americans' failure to qualify for the defence of their Olympic baseball title after a 2-1 loss to Mexico in Panama last November and another loss to Mexico to miss out on a place in the 16-team men's football competition.
If anything encapsulates America's struggling opening to the Olympics more it was their 92-73 basketball humbling to Puerto Rico on Sunday.
It was America's first Olympic defeat in the 25 games since National Basketball Association (NBA) players began playing at the Olympics with the Michael Jordan-led Dream Team at the 1992 Barcelona Games.
Co-captains Tim Duncan and Allen Iverson and rookie LeBron James were among the young collection of NBA millionaires embarrassed by a team that was crushed by the Americans in an exhibition game two weeks ago.
The result didn't go down too well back home with US papers describing Puerto Rico's Olympic upset as humiliating and suggesting that the nation that invented basketball had begun to take its supremacy for granted.
"US men's basketball falls flat on world stage," read the headline in USA Today. "The US men's basketball team was rocked, shocked, humiliated and exposed," it went on.
The New York Times dubbed it a "Wake-Up Call for Dream Team" and described how "Puerto Rican flags shook wildly as the American team... exited into a tunnel, beaten, stunned and embarrassed."
The 24-0 US run included three consecutive gold medals but now the squad must fight back in a preliminary group that also includes Lithuania, Australia, host nation Greece and Angola just to make the top four and the medal rounds.
There was another big splash in the swimming pool with America's crack women's 4x100m freestyle relay team going under to Australia on the opening night of competition on Saturday.
It the United States' first loss in the event since the former East Germany beat them in Seoul 1988.
Australian rocket Jodie Henry brought home her team to victory overhauling US Olympic icon Jenny Thompson to grab gold and a world record.
Not since the halcyon days of Dawn Fraser at the 1956 Melbourne Olympics have Australia won the women's sprint relay.
Thompson, 31, who had anchored the United States to victory in the event in the last three Olympics, said of Olympic debutante Henry's finishing surge: "It was a change of pace to be passed by someone. Usually it's the other way around."
Even South Africa joined in the act with a world record-breaking men's 4x100m freestyle relay which sank Michael Phelps and company on Sunday.
"We wanted to do better, but this is what we had," Phelps said after the Americans claimed bronze behind the South Africans.
"These are the four fastest guys we had. This is only the second time in history we got beat."
The significant reverses came after Friday's lavish Opening Ceremony when restrained US athletes were ordered to be on their best behaviour, wary of possible anti-American sentiment stemming from the conflict in Iraq.