LAS VEGAS -- Ronda Rousey rose to fame by handing out one-sided beatings. Her fall has occurred in the exact same fashion.

In her first appearance since a stunning knockout loss to Holly Holm last year, Rousey (12-2) suffered another lopsided defeat to defending bantamweight champion Amanda Nunes on Friday. The 135-pound championship fight headlined UFC 207 inside T-Mobile Arena.

Referee Herb Dean stopped the fight just 48 seconds in, as Nunes (14-4) rocked Rousey with right hands along the fence. Rousey did not go unconscious, as she did from Holm's infamous head kick, but she was essentially out on her feet. It is the fastest knockout finish of Nunes' career.

UFC women's bantamweight champ Amanda Nunes, right, scored the fastest knockout of her career, needing just 48 seconds to defeat Ronda Rousey in their main-event title bout Friday night at UFC 207. Christian Petersen/Getty Images

"I'm stopping everybody like that," Nunes said. "When I asked for this fight, I knew everything. I was preparing my mind, spirit, body. I know Ronda Rousey is big. They know and love Ronda Rousey, but no one is going to take this belt from me."

Rousey, 29, walked out of the Octagon without assistance. She did not immediately address the cameras or media. The UFC 207 fight week was unique in that Rousey did not participate in any traditional fight-week media obligations, saying she was focused only on winning the bout.

Appearing on SportsCenter after the fight, UFC president Dana White said he met with Rousey for about 45 minutes and said she was "in better spirits this time than she was after the Holly fight."

"She's very competitive. She does not like to lose," White said. "She loves to win, and she loves to do what she sets out to do. Tonight wasn't her night."

Asked whether he thinks Rousey will ever fight again, White said, "I don't know. Ronda obviously needs to go home and take some time. She's very rich. She doesn't need to fight anymore. She's super competitive. Maybe she wants to, I don't know. We'll see what happens."

Brad Slater, Rousey's agent, told ESPN's Ramona Shelburne: "It's too soon to say anything about the future. I don't want to speak for her. She's going to take some time to process this."

Slater also told ESPN that Rousey was medically cleared before leaving the arena. She did not have to go to the hospital, he said.

Nunes landed a very early jab on Rousey and then went immediately to the right hand. She is known as one of the harder hitters in the division, and Rousey looked hurt from basically the first exchange.

A former U.S. Olympic bronze medalist in judo, Rousey fell backward to the cage and then leaned forward to try to wrap Nunes up. Nunes shoved her back and continued to plod forward. Rousey managed to land one left hook as Nunes aggressively pursued her, but it didn't have much effect on the champ.

Once Rousey was dazed, she was an easy target for Nunes. Rousey did not shoot for a takedown and had no way of exiting Nunes' boxing range. Nunes' coaches from American Top Team and girlfriend Nina Ansaroff jumped up in celebration as Dean waved off the fight.

"When I connected her with my jab, I knew that she was going to go down and it happened," Nunes said. "I trained for everything that she would bring today. If she would come forward and try to take me down or if she respects me, I was ready for everything. I took my time and connected with some punches."

Rousey did not make any major changes to her camp following the loss to Holm. She prepared for this title fight at Glendale Fighting Club in Southern California, under striking coach Edmond Tarverdyan. She received a disclosed payday of $3 million. Nunes netted a disclosed purse of $200,000.

"Always when I see something wrong with my evolution, I try to make some changes," Nunes said. "I feel like [Rousey] doesn't know those things like a real fighter. I feel like if she doesn't know how to make some changes in her game, she's not a real fighter."

Nunes now holds the UFC female bantamweight record for most finishes inside the first round. She was tied with Rousey at five coming in. The Brazilian fighter won the title by submitting Miesha Tate in the first round at UFC 200 in July.

"Let's stop this Ronda Rousey nonsense because this fight was everything about her but I'm the champion," Nunes said. "I don't understand why. It's supposed to be everything about the champion and about the best in the world. Why did Ronda Rousey stop for a year and then come back and have everything? It's not right."

UFC 207 drew a $4.75 million live gate and a sell-out crowd of 18,533 at T-Mobile Arena, making it the most attended UFC event in Las Vegas.