Amanda Serrano retained her featherweight titles against Danila Ramos in the first women’s world title fight held over 12, three-minute rounds since 2007.
Serrano won by unanimous decision after dominating the contest in Orlando to maintain her grip on the WBO, WBA and IBF world featherweight titles and put herself in contention for a rematch against Katie Taylor, who has a rematch of her own with Chantelle Cameron next month.
The 35-year-old's WBC title was not on the line as the sanctioning body refuses to extend the length of rounds in women's boxing, citing "safety and well-being" concerns.
Women's bouts are usually contested over 10 two-minute rounds, with 16 years since the last time women contested a bout over three-minute rounds, when Layla McCarter defeated Donna Biggers and Melissa Hernandez in 2007 in fights scheduled for three-minute rounds.
But despite the extra workload, Serrano insists she could not tell the difference on the night, though Ramos was unable to push her to the limit.
"I went through the whole fight and I still have the energy to hold all my belts," said Serrano, who won all 12 rounds. "This was a historic night. I hope it's just the beginning, because I know there are a lot of women coming after me. I know the future is bright for us.
"In the sixth round, I was like, is it really three minutes or did they go back to two minutes?
"I felt good. I was in really good shape. I trained really hard for this fight knowing I had to go out there and prove to everybody, prove people right or prove people wrong, that women can do whatever they put their minds to."
Some fans have called for three-minute rounds with the theory that more time spent in the ring will increase the probability of a knockout and therefore make the bout more exciting.
PA contributed to this report