LAS VEGAS — After Amanda Nunes released the chokehold that finished her stunning victory at UFC 200 on Saturday night, the new bantamweight champion leaped onto the cage and pointed ecstatically at her girlfriend, Nina Ansaroff.

Nunes became the UFC’s first openly gay champion with her first-round submission of Miesha Tate. While the Brazilian bantamweight celebrated, Nunes also spared a thought for the history-making nature of her accomplishment.

“This is amazing,” Nunes said. “The most important thing is I’m happy with my life. … She means everything to me. This girl, she helped me every day.”

Nunes (13-4) and Ansaroff live and train together in Florida. While Ansaroff’s strawweight career hasn’t reached Nunes’ bantamweight heights, she has passionately supported Nunes’ rise in the crowded 135-pound division.

“She is so amazing, the most amazing person,” Nunes said. “I love her so much. … Nina is the best training partner I ever had in my life.”

Their teamwork showed in the upset win by Nunes, who wasn’t widely expected to become the UFC’s fourth bantamweight champion in nine months.

Nunes staggered Tate early with a precise right hand. She battered the champ throughout the round before easily sinking in the choke that forced Tate to tap out with 1:44 left in the round.

The fact that Nunes and Tate were the main event in the UFC’s landmark show was another milestone in the promotion’s enthusiastic embrace of women’s MMA.

In other featured fights:

Brock Lesnar returned from a 41/2-year UFC absence and won a unanimous decision over Mark Hunt.

Jose Aldo also won a competitive decision over Frankie Edgar to claim the interim featherweight title.

Daniel Cormier dominated a decision over Anderson Silva, who took the fight on two days’ notice after Jon Jones was dropped for failing a drug test.