Robert Whittaker reacts after his middleweight title bout against Yoel...

Robert Whittaker reacts after his middleweight title bout against Yoel Romero at UFC 225 in Chicago on June 10, 2018. Credit: AP/Jim Young

MELBOURNE, Australia — Australia's UFC middleweight champion Robert Whittaker has withdrawn from his championship defense against Kelvin Gastelum on Sunday at UFC 234 because of an abdominal injury.

UFC president Dana White says the 29-year-old Whittaker, who has a record of 20-4, became ill Saturday night and complained of pain in his abdomen before being diagnosed at a hospital with a hernia.

In a later statement, UFC said Whittaker had undergone emergency surgery due to a "severe abdominal injury."

The highly anticipated No. 1 contender match between rising New Zealand star Israel Adesanya (15-0) and Brazilian veteran Anderson Silva (34-8) will now serve as the main event on the Rod Laver Arena card.

Israel Adesanya reacts after defeating Derek Brunson during the first...

Israel Adesanya reacts after defeating Derek Brunson during the first round of a middleweight bout at UFC 230 at Madison Square Garden on Nov. 3, 2018. Credit: AP/Julio Cortez

It marks the second time Whittaker has been forced to withdraw from a scheduled title fight in Australia. Injuries kept him from fighting Luke Rockhold at UFC 221 in Perth last year.

Earlier this week, White had said the winners of the Whittaker-Gastelum and Adesanya-Silva fights would meet later this year.

SUBSCRIBE

Unlimited Digital AccessOnly 25¢for 6 months

ACT NOWSALE ENDS SOON | CANCEL ANYTIME