In what was supposed to be his first title defence, Australia's first UFC champion will face the man he fought and beat in his last outing. He will maintain the belt, win or lose.
Earlier this year, Romero weighed in at 187.7 pounds for a fight with Luke Rockhold for the interim belt.
Romero initially came in at 186lbs and was given an additional hour to get down to 185lbs for the much-anticipated rematch but he could only get as low as 185.2lbs, meaning he was ineligible to fight for the title.
Despite missing weight, Romero was able to score a knockout win over Rockhold.
Whittaker said: "I have a great team and a great staff".
Now recovered from a staph infection and a nasty case of chickenpox, Whittaker is ready to get back in the Octagon with the "Soldier of God".
"It's very hard. We come here to fight for the title", Romero said. This will be his second UFC fight ever. However, his second attempt had him at 0.2 pounds overweight.
CM Punk is the underdog in his UFC 225 fight tonight against Mike Jackson. At time of this writing, no official decision has been made as to whether the fight will still take place.
Gold Coast fighter Megan Anderson makes her debut against Holly Holm, a former champion best known for knocking out Ronda Rousey in Melbourne in 2015.