Ronda Rousey KO'd by Holly Holm in stunning UFC upset

Ronda Rousey was the UFC's unstoppable force until Holly Holm used the former champion's aggression against her to produce one of the sport's biggest upsets.

Rousey chased Holm around the ring at UFC 193 on Sunday in Melbourne looking for the right hold and taking head shots along the way until Holm saw an opening 59 seconds into the second round and snapped a kick to the head that immediately dropped her more fancied opponent to the canvas.

Holm (10-0) jumped on the prone Rousey, delivering several blows to her head before the referee intervened, ending Rousey's 12-fight unbeaten run and handing Holm the bantamweight title.

An ecstatic Holm jumped around the ring while Rousey stayed on the canvas as she received medical treatment amid the roar of a stunned, record UFC crowd.

"She's won a lot of fights and imposed her will on a lot of fighters," Holm said. "So I expected her to be aggressive and impose her will on me.

"She had me on the cage for a minute and obviously she was trying in for a take down right there ... she had a lot of things she was trying so I'm just glad I put in the practice," she added.

Rousey, a former judo Olympian, was unbeaten through 12 UFC fights before meeting Holm, and a win would have been her seventh title defense. Instead, Holm, a 34-year-old veteran female boxer from Albuquerque, New Mexico, has the championship belt.

"We figured her aggression was coming, if it didn't that's OK, but with footwork and my career we figured she wouldn't give me that space," Holm said. "There's been a lot of blood, sweat and tears but it was all worth it."

Rousey on Sunday released a statement thanking the fans for their concern and promising to make a comeback

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Rousey left the stadium to receive treatment for concussion and facial cuts at a nearby hospital after the loss and skipped the post-fight media conference.

"She was transported [to hospital]because she got knocked out," UFC chief Dana White said. "Obviously she's completely bummed out and depressed."

White said a rematch between Holm and Rousey made "a lot of sense" and would put other potential matchups on the backburner.

"Obviously we don't make fights the night of the fight, but the rematch makes a lot of sense," he said. "The rematch is what the people want to see."

Organizers announced a crowd of 56,214 at Melbourne's Etihad Stadium, which normally hosts Australian rules football matches. The mark eclipsed the 55,724 fans who attended UFC 129 at Toronto's Rogers Centre in 2011.

Rousey, 28, has taken UFC by storm since her debut in 2012 and her success has led to several movie projects as well the publishing of her autobiography.

But it was Holm's calm confidence and the manner of her win that attracted all the attention Sunday.

"Tonight was one of those moments," White said. "These are the moments in fighting that make it so crazy and so fun. Tonight was one of those moments."

Holm, a former undisputed welterweight boxing champion, said the moment of her UFC title victory was "one of those moments that you live for."

"They're the scariest moments. This fight was a lot for me mentally," she added. "I couldn't tell you how many times I cried in the gym leading up to this fight.