The UFC Sacramento main event lasted all of 16 seconds, as Germaine de Randamie dropped Aspen Ladd with a right hand to the face to prompt a stoppage.
Ladd was upset about the early stoppage, as were the fans who booed the decision from referee Herb Dean.
For Canadian viewers:
De Randamie, the No. 1 contender in the bantamweight division, earned her fifth consecutive victory. The Dutchwoman's last loss was to Amanda Nunes, the current bantamweight champion.
"I dropped her and she didn't know where she was. It was a nice clean shot and a good stoppage," De Randamie said after the fight.
Ladd, meanwhile, lost for the first time since beginning her professional career in mixed martial arts with eight straight wins.