Holly Holm KOs Ronda Rousey in second round of UFC 193

Holly Holm, ranked just eighth in their weight class and underwhelming in her two previous U.F.C. fights, knocked Rousey out in the second round.

Rousey started the fight on the attack, perhaps looking for another quick win. But she found herself chasing Holm around the Octagon, all the time taking hard punches and kicks. She struggled to get Holm on the ground, thanks in part to Holm’s superior reach. Even when Rousey began to apply her signature armbar, Holm eluded it and continued the barrage. A nasty kick to the head finished Rousey off.

Holm, 34, was 33-2-3 as a boxer, holding W.B.A., W.B.C. and numerous other titles. She then transitioned to M.M.A., where her record improved to 10-0 with the Rousey win.

What’s next for Rousey? At 28, she is young for the Octagon. The median age of a U.F.C. champ is currently 31, and only two champions are younger than Rousey. The U.F.C. president, Dana White, suggested immediately that a rematch would be in the offing. Rousey had turned into the U.F.C.’s most marketable star, male or female, and it is in everyone’s interest to keep her front and center.

Rousey was taken to a hospital to be checked after the fight and did not make a postfight statement. But in a brief post on Instagram on Monday, she wrote, “I’m going to take a little bit of time, but I’ll be back.”