INDIANAPOLIS, AUG. 17 -- The U.S. boxing team's winning streak in the Pan American Games was halted by Cuba tonight, the Americans losing three quarterfinal bouts in varying and equally discouraging fashion.

Adalberto Regalado made national champion Arthur Johnson the first American in nine matches to fall with a 3-2 decision in a stirring, hard-to-call flyweight bout. Then Julio Gonzalez won a unanimous 5-0 decision over young lightweight Patrick Byrd. The final indignity came when Cuba's Angel Espinosa decked U.S. world middleweight champion Darin Allen with a right to the chin that stopped their bout just 1:35 into the first round.

"I'm definitely not in the most happy mood," U.S. coach Roosevelt Sanders said.

There was one victory. U.S. welterweight world champion Kenneth Gould redeemed the night somewhat with his quarterfinal victory over Osvaldo Checa of Panama. Gould clinched a bronze medal with his 5-0 decision. But so did Regalado, Gonzalez and Espinosa for Cuba. Just one other American has made the semifinals: Kelcie Banks of Chicago, with a 3-2 decision over Cuba's Arnaldo Mesa on Sunday.

"The Americans had a win streak going, and being the first to lose does not feel good at all," Johnson said. "Especially if you thought you won.

Johnson, a three-time national champion and the only U.S. winner of a gold medal in the Goodwill Games, said he was contemplating retirement following his bout.

A Minneapolis college student, Johnson said he might not wait for the Olympic Games before retiring. He added that it had little to do with tonight's loss; it was a question of pursuing a degree in broadcasting.

"I'll take a while and let it soak in," he said. "Right now I feel like I want to give it up. There's more to life than boxing."

Byrd's loss was not surprising. The 18-year-old from Flint, Mich., was fighting in his first major international competition and showed it. Gonzalez displayed all the movement and style in the bout; Byrd merely demonstrated some impressive punches and avoided a knockout. "He had quality," Gonzalez said graciously.

Allen's defeat was shockingly quick. The blow from Espinosa was a short right uppercut that caught him flush on the chin. It was the second knockout he has suffered to Espinosa, the first coming last December in a dual match. Although Allen was the 1986 world champion, Espinosa also has a world title, which he won as a light middleweight before moving up.

The quarterfinals will be completed Tuesday when three more Americans fight. Bantamweight Michael Collins of LaPorte, Tex., meets Patrick Stephenson of Jamaica in the 119-pound division. Todd Foster, a light welterweight from Great Falls, Mont., meets Oscar Caton of Argentina at 139 pounds. Frank Liles of Syracuse, N.Y., meets Peter Silva of Peru at 156 pounds.

Wednesday, Andrew Maynard, a U.S. Army boxer out of Cheverly, Md., meets Cuban Pablo Romero in the light heavyweight semifinals.