The women's bantamweight title bout was the main event of UFC 170 event at Mandalay Bay Events Center in Las Vegas.
Both fighters came out swinging right away, and after the dust settled, Rousey pushed the challenger to the fence and landed knees on her. Rousey looked for an opportunity for her trademark judo throw. But McMann defended it.
But soon after, Rousey hit McMann with a knee to the body. She followed it with an elbow, another knee, another elbow - and then a final knee that put McMann on the canvas.
Once there, Rousey was quick to pile on with three strikes before referee Herb Dean jumped in to stop the fight. McMann wasn't covering up.
The crowd booed what it deemed was an early stoppage. But for the first time in her career, Rousey had a non-armbar finish. The TKO win came just 66 seconds into the fight.
"We studied her videos and knew it was the best thing to concentrate on the liver shot for this camp," Rousey said. "The knee has been working for me the most throughout sparring in this camp."
McMann stayed gracious in defeat and wouldn't say Dean's stoppage was early.
"I thought it was a good fight. I got hit in the liver, and no matter how hard you train, you can't get your liver stronger," McMann said. "I hope to get a rematch and come back here and put on a better fight. I was trying to get back up, but it's my own fault. I should've gotten back to my feet quicker."
Rousey (9-0 mixed martial arts, 3-0 UFC) stayed unbeaten and notched another first-round win, the eighth of her career. McMann (7-1, 1-1) suffered the first loss of her MMA career.
Full UFC 170 results:
Ronda Rousey def. Sara McMann via TKO (strikes) - Round 1 (1:06)
Daniel Cormier def. Patrick Cummins via TKO (punches) - Round 1 (1:19)
Rory MacDonald def. Demain Maia via unanimous decision (29-28, 29-28, 29-28)
Mike Pyle def. T.J. Waldburger via TKO (strikes) - Round 3 (4:03)
Stephen Thompson def. Robert Whittaker via TKO (strikes) - Round 1 (3:43)
Alexis Davis def. Jessica Eye via split decision (28-29, 29-28, 29-28)
Raphael Assuncao def. Pedro Munhoz via unanimous decision (30-27, 30-27, 30-27)
Aljamain Sterling def. Cody Gibson via unanimous decision (29-28, 29-28, 29-28)
Zach Makovsky def. Josh Sampo via unanimous decision (30-27, 30-27, 29-28)
Erik Koch def. Rafaello Oliveira via TKO (punches) - Round 1 (1:24)
Ernest Chavez def. Yosdenis Cedeno via split decision (28-29, 29-28, 30-27)
Matt Erickson writes for MMAjunkie.com, part of the USA TODAY Sports Media Group.
Bio DATA Donda Jean Rousey
Ronda Jean Rousey is an American mixed martial artist, judoka and actress. She is the first and current UFC Women's Bantamweight Champion, as well as the last Strikeforce Women's Bantamweight Champion. Wikipedia