UFC strawweight Mackenzie Dern avenged a loss from five years ago to Amanda Ribas on Saturday when she submitted Ribas via armbar with just four seconds left in the third round.

Dern (15-5), a submission specialist, used the threat of an armbar from her back to go all out late in the round. Once there, she isolated Ribas’ left arm, which delivered the punch.

The 115-pound bout headlined the first UFC event of 2025 at the Apex facility in Las Vegas.

“It sucks when you’re so close (to a submission) and the time is almost up,” Dern said. “I am very happy that I got the title. I try to work on my punches, my takedowns. (Ribas) is such a tough fighter with her judo. We still have a lot to do, but it’s great to get that win from five years ago.”

Ribas (13-6) defeated Dern in a three-round decision in 2019. She stuffed all six of Dern’s takedown attempts in that first meeting, giving them an advantage in strikes when fighting on the feet and on the ground.

Ribas again did a good job of defending Dern’s grappling on Saturday, but Dern set up submissions from her back and scrambled to switch positions.

It’s a huge win for Dern, who has dominated the non-ranked competition but has struggled to pick up wins against elite competition. She entered Saturday’s main event as the No. 6 ranked strawweight in the UFC. She is now on a two-fight winning streak, including a decision over Lupita Godinez in August. Ribas was in 8th place at the start of the weekend.

Dern, 31, transitioned to MMA in 2016 and was still developing for much of her UFC career. She outscored Ribas by a total of 98-80 punches on Saturday and cut an elbow off her back in the second round. She was 0-for-6 on takedown attempts in their 2019 meet.

Dern has already fought four of the five title contenders ranked ahead of her, with an overall record of 1-3. She declined to call a future opponent. The only woman ranked ahead of her, Tatiana Suarez, is currently booked to challenge defending champion Zhang Weili at UFC 312 in February. The outcome of this fight should impact Dern’s eventual title path.