UFC President Dana White announced Friday night that welterweight champion Robbie Lawler injured his thumb Friday and was ruled out of his scheduled Nov. 14 title defense against Carlos Condit.
Rousey (12-0) will take on former professional boxing champion Holly Holm (9-0) as the main event at an outdoor stadium in Melbourne.
The UFC has yet to determine the new Jan. 2 main event.
Lawler (26-10) made his first title defense in July, scoring a technical knockout of Rory MacDonald in one of the UFC’s most compelling fights in history.
Condit (30-8) defeated former welterweight title challenger Thiago Alves in May to earn his second title shot.
Venice's Rousey defeated Bethe Correia in 34 seconds on Aug. 1, and she’s beaten her last four opponents in a combined 2 minutes 10 seconds.