UFC 127 in Sydney sold out in 30 minutes, equalling the UFC record set earlier this year by UFC 115 in Vancouver.
The mixed martial arts card is scheduled for Feb. 27 at the Acer Arena. The main events features B.J. Penn versus Jon Fitch.
UFC 110, the UFC's first foray into Australia last February, set an arena box office record and sold out within two hours.
The speed of the 127 sales means that two of the UFC's top five sellouts are in Australia (UFC 110 ranks No. 4). The other three are all in Canada: UFC 115 in Vancouver and UFC 83 and 97 in Montreal.
Promoters have added 600 seats for this latest Sydney show.
"We will have just over 18,000 fans in attendance at UFC 127 in nine weeks' time and expect to blow the roof off," Marshall Zelaznik, the UFC's managing director of international development, said in a statement.
"Over the last 18 months, Australia has become one of the top three or four markets in the world for us," he added.
UFC 127 will be screened around the world in the usual time slot for UFC events, meaning the event takes place Feb. 26 in North America.