Puerto Rico’s unexpected romp over the American basketball team yesterday, one of the greatest sports achievements in the territory’s history, had fans cheering wildly from San Juan to the streets of Spanish Harlem.

“USA got smacked,” said Oscar Arrieta,17,a student in the South Bronx. “If they lost, I thought they’d lose by a little bit, but not get smacked.”

The defeat, America’s first since adding the pros and only the third in the team’s Olympic history, did little to hurt the chance of gold, but it was a miraculous triumph for the island territory.

With the odds stacked way against them – Puerto Rico had lost to America five times in the past 13 months – the island led 33 minutes of the 40-minute game. The spirited team found a weakness in the Americans’ zone defense and rallied behind Utah Jazz guard Carlos Arroya, who led the squad with 24 points in the 92-73 win.

As Mr. Arroya left the court he showed off the Puerto Rico inscribed on his jersey.

“That was him telling his island of 4 million people he was very proud to beat the big colossal from the north,” Puerto Rico’s coach, Julio Toro, said.

On the island, Puerto Ricans celebrated the island’s historic win as if it were gold, honking horns and waving Puerto Rican flags after the game. The response in New York’s Puerto Rican neighborhoods was joyous – if not as loud.

“It’s a beautiful victory for us,” said Juan Nieves, a native of Puerto Rico, savoring the victory with friends in East Harlem yesterday afternoon .”The U.S. is very powerful and it’s great that we won.”

But even Mr. Nieves, who described himself as a “fanatic of the NBA and Puerto Rico” skipped this opening game, and had to hear the news from salesman at his local bodega.

Roberto Ayalo, owner of the restaurant and bar La Fonda Boricua, hugged family members, jumped, and shrieked with joy at home when victory came.

“This year was our year. It was a big victory no matter what we do now,” said Mr. Ayalo, 39, who moved to New York from Puerto Rico four years ago. “Our team is Puerto Rican team, they are not millionaires. On our island they don’t live from basketball, they all have day jobs.”

City Council Member Jose M. Serrano, who represents the South Bronx, received a call from his father, Rep. Jose E. Serrano, alerting him Puerto Rico was ahead and he better turn on the game.

“It was sort of a David and Goliath situation,” the younger Mr. Serrano said. “Here was Puerto Rico playing hard and doing all the big shots when the needed to.”

The councilman credits the Puerto Rican basketball players, many of them who got their starts on the courts of New York, for the dedication to the sport that drove the win.

“I think the Puerto Rican national team exemplifies their hard work,” he said, adding the victory “is a pretty good wakeup call for the U.S. squad that they need to get their act together if they’re going to win the gold.”

Still, he said, Americans should not take the loss to heart. “It was really Americans beating Americans because everyone in the island of Puerto Rico is an American citizen,” Mr. Serrano said.

That said, if the two teams were to meet again there would be no conflict of interest: “I confess, I will be rooting for Puerto Rico.”