Sena Agbeko lost his unbeaten record when Raymond Gatica stopped him in the fourth round in Hammond, Indiana, on Friday night.
The Ghanaian also failed to get through to the semifinals of the middleweight tournament in which they were competing.
Agbeko was in trouble in the third round and the fight was stopped 66 seconds into the fourth. His record now stands at 15-1, with 15 knockouts. Gatica, from Texas, improved his record to 14-2; 6.
On the same bill of a tournament broadcast live on SuperSport, Willie Monroe beat Donatas Bondas by 59-55 on two cards and 58-56 on the third to go through to the next round.
Monroe has lost once in 17 fights and has stopped 6 of his opponents. Bondas now stands at 18-5-1, with 6 wins inside the distance.
The 21-year-old Agbeko, a former Ghanaian judo champion with a diploma in journalism, disappointed in his US debut after winning each of his 15 professional fights inside the distance.
After stoping the likes of Francis Mensah and George Amuzu in Accra, where all his fights had taken place, Agbeko failed to take charge at the start and was soon on his way back to the dressing rooms.
BURNS RETURNS FROM BROKEN JAW
In another fight to be broadcast live on SuperSport, Scottish star Ricky Burns defends his WBO lightweight title against American Terence Crawford in Glasgow on Saturday night.
Burns, a former WBO super-featherweight champion, won the lightweight title when he beat Namibian Paulus Moses in March 2012.
He suffered a broken jaw when he beat Raymundo Beltran last September and can expect another bruising encounter against the American, the mandatory challenger.
Crawford, 26, has not lost in 22 professional fights and won 16 of them inside the distance. Burns, 30, has won 11 of his 39 fights by knockout. He lost twice and drew once.
Live coverage of the fight will be broadcast on SuperSport 7 on DStv starting at 11pm.
And a couple of hours later, at 3am on Sunday, viewers can watch the super-middleweight rematch between Julio Cesar Chavez Jr and Bryan Vera in San Antonio, Texas. The action will be on HD 5 and SS Maximo (channel 221).
When they fought in September last year, Chavez won on points. The result triggered a huge outcry among Vera’s fans and critics all over the United States.
Earlier on the bill, Orlando Salido defends his WBO featherweight title against Vasyl Lomachenko and Juan Diaz takes on Gerardo Robies over ten rounds in a lightweight fight.