The biggest shock in UFC history happened in the early hours of Sunday, November 15 in Melbourne.
Holly Holm sends undefeated champ to hospital after knock-out
Rousey was hot favourite for the fight having been undefeated throughout her professional career.
Bantamweight champion Ronda Rousey was knocked out cold by Holly Holm in front of a record crowd of 56,214 in Melbourne in the UFC Women's Bantamweight Championship.
She however struggled to cope with the strikes from Holm and was knocked out cold in the second round.
Rousey attacked Holm as the fight begun and it was thought that the champ would carry the day.
But Holm had the switch to mixed martial arts four years ago, was expected to ask new questions of Rousey with her superior stand-up game and footwork and she did just that.
She dodged strikes from Rousey and with just over a minute remaining in the second round aimed a kick to her head which left the former undefeated champ on the ground.
In Rousey's previous six defences of her title, she had been taken beyond the first round just once, by Miesha Tate in their rematch in 2013, and her last three fights had lasted a combined one minute and 47 seconds.
She was however knocked out cold in the second round and UFC president Dana White later confirmed Rousey had been taken to hospital.
Watch the highlights of the fight below:
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