And yet, much like Mike Tyson met his comeuppance at the hands of Buster Douglas in a stadium halfway around the world a generation ago, Holm, the former world boxing champion, put in a flawless performance against the biggest star in mixed martial arts in front of a potential record crowd in Melbourne, Australia.
Holm (10-0) absolutely dominated the previously invincible Rousey in the main event of UFC 193 on Saturday night before finishing her with a brutal head kick knockout at the 59-second mark of the second round to claim the UFC bantamweight title.
"I've never spent this much time in the gym than I have for any fight," said Holm, a 34-year-old JacksonWink MMA fighter. "It really all came together."
Rousey (12-1) came out and pushed an aggressive pace from the outset, but it turned out not to be a smart tactic against a fighter who had 38 pro boxing fights under her belt before ever turning to MMA. Holm figured out Rousey's timing, used front kicks to keep her from moving in, and repeatedly tagged the stationary Rousey as she stood in front of Holm.
By the later moments of the opening round, Rousey was bloodied, tiring, and sloppy. It got worse in the second round, as Holm continued to pick Rousey apart. A picture perfect head-kick dropped Rousey cold. Holm landed a right hand to the grounded Rousey before referee Herb Dean waved off the bout at 0:59.
The finish was a stunning conclusion to a tumultuous several-week period in which dissension swirled around the Rousey camp. First, Rousey's mother, Dr. Ann Maria DeMars, openly blasted Rousey's head coach, Edmund Tarverdyan. Then Tarvedyan's financial woes and bankruptcy case came to light. Then Rousey hung up on a media call when asked about her relationship with UFC fighter Travis Browne, who was accused of domestic abuse by his previous girlfriend (He has not been charged for the alleged actions).
Finally, at Friday's weigh-ins, Rousey came unglued during the traditional posedown while Holm kept her cool, a foreshadowing of things to come.