The Welsh pair of Andrew Selby at flyweight and welterweight Fred Evans get their chance to become the first Welsh boxers since Ralph Evans in 1972 to win Olympic medals when they fight in today's quarter-finals.
The pair, who have become random fighting buddies because of the draw, also became the first Welsh boxers in 86 years to win European amateur titles last year in Ankara.
Selby will be in the ring first and appears to have the most difficult task of the two when he meets the unseeded young Cuban Robeisy Ramirez, one of about a dozen world-ranked boxers to slip under the seeding radar. Ramirez has looked excellent in both of his bouts to reach today's quarters.
"It's not easy to progress in the Olympics and when some of the fighters are not seeded it can mean that every bout is hard," said Robert McCracken, the performance director of GB boxing. "Selby had a tough, tough draw. It's that simple. Natasha [Jonas] had the same tough draw."
Selby lost in the final of last year's World Championships in Baku to the brilliant Misha Aloian and the Russian, in theory, will be waiting in Sunday's final.
"I have wanted another go at Aloian since losing and this time I know I can beat him," said Selby.
Evans, who is now the youngest member of the team at 21, has won twice since the tournament started and was not given a seeding, which meant that in his second bout he had to overcome Lithuania's Egidijus Kavaliauskas. It was close, tense and at the end Evans was a clear winner over the man who had stopped him at the World Championships last year.
In today's quarter-finals Evans fights Canada's Custio Clayton and, like so many British boxers here at the ExCeL, he starts as a favourite. Clayton has scrambled through two contests and Evans, provided he can start fast, should make Friday's semi-finals.
In another of the welterweight quarter-finals the last surviving American boxer Errol Spence returns to action, having lost his last fight 13-11 to India's Krishan Vikas. At the end of the contest the American team appealed against the verdict, claiming the referee had not been strict enough. It was decided by an International Boxing Association (AIBA) commission that Vikas held on nine occasions and deliberately spat his gumshield out, which is illegal in amateur boxing
The Indian boxer was given a belated two public warnings and Spence collected four extra points to win 15-13.
"I was not meant to go home and now I will get the chance to show what I can do," promised Spence, who had minutes earlier announced that he was turning professional. The other eight American male losers are all thought to be heading to the pro ranks.
It is unusual for any decision to be reversed in amateur boxing but so far two have been changed here, which in many ways is a compliment to the transparency of AIBA, the sport's governing body.