Making the development even more bitter is that almost this same thing happened a year ago with the same fighter, the same country and the same belt on the line.
It's obviously a huge blow to Whittaker, 28, who was forced to pull out of a title defense on home soil in February 2018. He was diagnosed with an abdominal hernia.
It means the no less anticipated co-main event between Israel "The Last Stylebender" Adesanya and Brazilian legend Anderson Silva will top proceedings Down Under.
"It wasn't a weight-cutting related issue or anything like that, it's just a very unfortunate hernia issue which may even require a procedure".
A devastated Whittaker was set to undergo surgery on Sunday after the hernia left him vomiting the night before.
UFC 234 takes place Saturday at Rod Laver Arena in Melbourne, Australia.
With next to no time to find a replacement for Whittaker all the way out in Australia, UFC 234 turned to its old superstar in Silva to headline the event.
"Kelvin is the biggest hurdle in my way, and he's a true test", Whittaker said. Injuries kept him from fighting Luke Rockhold at UFC 221 in Perth past year.
Upon his entry, Adesanya was compared to former light heavyweight champion Jon Jones in fight style and appearance, but the announcement of a fight against middleweight veteran Anderson Silva quickly turned heads. "I look forward to learning something from it and growing".