PORTLAND, Ore. (AP) _ The U.S. Olympic boxing team, led by dominant perfomances from Floyd Mayweather and Nate Jones, won nine of 12 matches against their German counterparts Friday night.

Jones, a heavyweight from Chicago, defeated Peer Muller when the referee stopped the bout 1:40 into the second round. Jones led 14-2 on points when he connected with a hard right to the head that stunned his opponent. After a standing eight-count, the referee awarded Jones the fight.

Mayweather, 19, from Grand Rapids, Mich., defeated Michael Hammer 19-1 in their 125-pound match. Mayweather knocked Hammer to the canvas in the second round with a strong left-right combination.

U.S. coach Jesse Ravelo praised the performances of Mayweather and Jones, both of whom will fight in the 1996 Olympics in Atlanta. Friday night's bouts featured six Olympians and six alternates on the U.S. team. The same format will be used when the United States meets Russia in Portland next month.

``Both Mayweather and Jones beat good fighters,'' Ravelo said. ``It just showed that they are in good shape. They looked great and they'll get better during the next couple of months.''

Ravelo also liked the work of super heavyweight Joseph Mesi, an alternate from Tonawada, N.Y.

``He brawled with the guy because we knew he had to get inside and take away the reach advantage the German had,'' Ravelo said.

Other U.S. winners were:

_ Ramases Patterson, River Rouge, La., defeated Zoltan Lunka 24-17 at 112 pounds.

_ Jermaine Fields, Washington, D.C., outpointed Heiko Hinz 21-14 at 132 pounds.

_ Fareed Samad, U.S. Army, outscored Enrico Thormann 8-2 at 147 pounds.

_ Antonio Tarver, Orlando, Fla., claimed a 9-5 decision over Thomas Ulrich at 178 pounds.

U.S. boxers Albert Guardado (106) and David Reid (156) won by defualt when their opponents weren't available to fight.

Ravelo was disappointed with the performance of Tarver, a southpaw who is expected to be one of the U.S. team's medal hopefuls.

``He fought a tough guy, but he needs to be more aggressive and not so timid with his punches,'' Ravelo said. ``He needs some work, but he is capable. He'll be OK.''

Ravelo liked what he saw against the Germans, who got wins from Dirk Kruger, Oktay Urkal, and Sven Ottke.

``We have a lot of work to do, but they showed me some toughness tonight,'' Ravelo said. ``We're in pretty good condition, which helps.''