Pat McCormack was limited to a silver medal after he was beaten by Cuba's Roniel Iglesias via unanimous decision in the Olympic welterweight final.
Team GB will claim an all-time record haul of six boxing medals at these Games, but McCormack was denied their first gold in Tokyo by the veteran Iglesias.
Iglesias won bronze at Beijing in 2008 and gold at London 2012 - in his fourth Games, he was too much for Sunderland fighter McCormack.
McCormack found a home for his right hand and even a left hook while on his back foot, but Iglesias was setting a frantic pace.
McCormack was on the floor inside the opening exchanges of the second round after a big Iglesias left hand. The referee, however, did not score it as a knock-down.
McCormack was competitive throughout the rest of the fight but Iglesias was faster and sharper. In the last exchange, Iglesias stung McCormack with a statement of a left hand.
McCormack had been the No 1 seed at welterweight. He was a veteran of Rio 2016 and the 2018 Commonwealth Games champion.
His twin, Luke, was also eliminated by an excellent Cuban in Andy Cruz.
But despite defeat in their first final, this has already been a hugely successful Olympics for Team GB's boxers.
Ben Whittaker will fight in the gold medal light-heavyweight match on Wednesday.
Frazer Clarke at super-heavyweight, Galal Yafai at flyweight and Lauren Price at middleweight are set to compete in semi-final fights so are guaranteed at least a bronze medal.
Karriss Artingstall has already earned a bronze.