Floyd Favors' luck ran out tonight. The world bantamweight champion from Capitol Heights, Md., abandoned his usual classy style in search of a knockout and instead dropped a 4-1 decision to Manuel Vilchez of Venezuela in the semifinals of the Pan American Games.

Favors' setback was one of a series for U.S. boxers. After Paul Gonzalez advanced to the light flyweight final by scoring the 12th straight U.S. victory in this competition, everything went downhill.

World flyweight champion Steve McCrory, Favors and featherweight Bernard Gray all dropped split decisions, to the delight of the packed house at Parque Estadio Nacionales.

It was fear of the crowd's influence on the judges that prompted Favors to seek a knockout against the taller Vilchez. It obviously backfired, as the fans roared for some wild rights by Vilchez that hit nothing but shoulder, and the nonstop action created bedlam.

"I think I deserved to lose," Favors said. "I used to be a master boxer-puncher and here I was just rushing around. I knew I had to knock him out to win. In a close bout, the guy who has the crowd's side will get it. The judges hear the noise even when he misses and they're influenced. But I don't take anything from him. He's a good boxer."

Gonzales used a big edge in size and reach to gain a 5-0 verdict over Manuelito dos Santos of Brazil. Dos Santos took a standing-eight count in the third round and also was penalized for holding.

McCrory was upset by Laureano Ramirez of the Dominican Republic, who retreated most of the fight and then occasionally charged like a bull, throwing flurries of punches that did little damage.

Gray lost a weird decision to Santos Cardona of Puerto Rico. The judges somehow came up with a 3-2 verdict in favor of Gray, who was twice penalized for holding during an uninspired performance.

All 3-2 decisions go to a jury of five--who sit directly behind the judges--for confirmation. In this case, the jury overruled the judges, 4-1.

It was a bad day for the United States. Hurdler Judi Brown, tennis player Gretchen Rush and cyclist David Grylls collected the only gold medals.

Even with such an unproductive day, the United States still had stockpiled 92 golds and 195 total medals, well ahead of second-place Cuba's totals of 60 and 125. Canada was running third with 11 and 80. The Americans also collected only three golds on opening day.

The American basketball players, the only undefeated nation in the two weeks of the men's tournament, exploded early behind point guard Leon Wood's shooting and playmaking and handed Mexico its first defeat of the final round 81-68. The United States is 2-0 in the five-day finals.

In track and field, the depleted United States team suffered through a disappointing second day of competition, with favorites Jackie Washington and James King being upset and two women forced to withdraw because of injuries.

The powerful Cuban team capitalized on the poor showing by the Americans to take five of the nine gold medals awarded.

The Americans, hit hard by the pullout of 12 male athletes Tuesday, lost two of its top women's hopes when decathlete Marlene Harmon of Canoga Park, Calif., suffered an ankle injury in the decathlon's first event and Lisa Hopkins of Los Angeles did not make it to the women's 100-meter final after aggravating a groin injury.

Washington, of Houston, was shocked in the women's 100-meter final by Esmeralda Garcia of Brazil, who trailed Washington with 10 meters to go but had a better dip at the tape to snatch the gold in 11.31. Washington was second in 11.33 and Lisa Ferrer of Cuba was third in 11:38.

Lisa Hopkins of Los Angeles was forced to withdraw from the final after aggravating a groin pull injury following her semifinal race Tuesday.

In the men's 400-meter hurdles, King of San Diego could only manage the bronze medal in a disappointing 50.31. Frank Monthie of Cuba was first in 50.02, barely beating the 50.08 by Antonio Diaz Ferreira of Brazil.