It's "martial" and it's "art," but it's also "mixed," and this third component is critical. Greg Jackson, the sport's foremost trainer, likens fighters' skills to four-legged tables. The legs are wrestling, jujitsu, kickboxing and boxing, and if one is shorter than the others, then the structure becomes rickety.

This was illustrated on Sunday at UFC 193 in Melbourne. In the biggest upset in the sport's history, Holly Holm didn't merely defeat Ronda Rousey; she knocked her out cold in the second round of their bantamweight title fight.

For Holm (right), an 18-to-1 underdog, surviving the first round—a claim only one of Rousey's 12 pro opponents could make—would have marked an achievement. The short leg of Rousey's table, though, is her boxing, which is also Holm's strength. She was a champ—with wins over Mia St. John and Christy Martin—before gravitating to MMA. Holm, 34, married slick footwork with heavy punching, bloodying Rousey with jabs and preventing the 28-year-old champ from taking her to the ground, where she could deploy her signature arm bar. A minute into the second round, Holm slipped a left hand and then followed with the knockout blow, a left kick—Holm was also a top kickboxer in her pre-MMA life—that caught Rousey under her right ear.

A rematch is inevitable, perhaps as early as the summer of 2016. Until then, Rousey will work on throwing and avoiding punches, trying to rebuild a table that, unexpectedly and spectacularly, toppled.

PHOTOQUINN ROONEY/GETTY IMAGES (HOLM)

HOLE YARDS PAR R1 R2 R3 R4
OUT
HOLE YARDS PAR R1 R2 R3 R4
IN
Eagle (-2)
Birdie (-1)
Bogey (+1)
Double Bogey (+2)