Alycia Baumgardner, an undisputed world champion at super-featherweight, moved up to lightweight to capture the IBF world title when she shut out Elif Tur Nurhan in Texas.
Baumgardner won a unanimous decision after 10 rounds as she overcame Nurhan at College Park Center in Arlington.
The American won 100-90 on all three cards, beating a hard puncher who had never lost before.
Baumgardner hurt Turhan at times, shaking her up in the third and seventh rounds.
Turhan was under real pressure at the end of the third, when a mistake granted her a fortunate reprieve. The action was briefly halted when the 10-second clapper was mistaken for the bell.
"I hit her, I've seen her legs wobble, [I thought:] 'We got her' and then the bell rang or something happened," Baumgardner said.
"Back to business though. Those moments can happen in a fight. It's about staying composed."
Baumgardner poured in punches, with Nurhan feeling the weight of those attacks too in the ninth round. Nurhan went the distance but, despite her punch power, could not threaten Baumgardner.
Now the IBF champion, Baumgardner looks to be on a collision course with Caroline Dubois, who fights Stephanie Han for the WBA, WBC and WBO 135lb titles on February 20, live on Sky Sports.
Baumgardner and Dubois have clashed before and the Briton was ringside in Texas. Their war of words continued after the American's latest win.
"Are we going to fight?" Dubois demanded.
"You've got a champ right there in front of you," Baumgardner warned.
Ramla Ali took a contentious split-decision victory over Mikiah Kreps to win the WBO and IBF super-bantamweight titles.
Ali started sharply and knocked Kreps down with a right hook right on the chin in the third round. From then on, though, Kreps maintained real pressure on Ali and the two finished trading punches before the final bell.
Kreps won widely, 98-91, for one judge but Ali took it 96-93 and 97-92 on the other two cards.
It was an emotional victory for Ali, whose family had to flee Somalia when she was a child and settled in London. She dedicated the victory to the memory of her father who passed away earlier this year.
Skye Nicolson defended the WBC super-bantamweight title, beating Japan's Miyo Yoshida, winning a unanimous decision on a dominant display.
Nicolson took the victory 100-90, 99-91 and 98-92.
Yoshida found moments of success on the inside, landing right hands in the sixth and eighth rounds, but Nicolson continued to counter effectively with straight lefts and rights. Nicolson closed out her commanding performance with sharp uppercuts and a three-punch combination in the 10th round.
Unbeaten prospect Albina Moldazhanova knocked out former European champion Kirstie Bavington, subjecting her to heavy punishment before landing a right hook in the fourth round to finish it inside the distance. Moldazhanova has a 100 per cent knockout ratio after six pro fights.
Watch Caroline Dubois vs Stephanie Han on February 20, live on Sky Sports.
