Israel Adesanya has his next challenger and the UFC has its Australia headliner.

Adesanya will defend his UFC middleweight title against Sean Strickland in the main event of UFC 293 on Sept. 9 in Sydney, UFC president Dana White announced Tuesday.

ESPN has Adesanya No. 4 in the world pound-for-pound rankings and No. 1 at middleweight. Strickland is ESPN's No. 8 middleweight.

Adesanya-Strickland was not the initial plan for the UFC 293 main event, sources told ESPN. The UFC was hoping Adesanya, a New Zealand resident born in Nigeria, would defend the title against the winner of a fight between Adesanya rival Robert Whittaker and Dricus Du Plessis at UFC 290 on July 8. Du Plessis impressively finished Whittaker via TKO in the second round, and Adesanya and Du Plessis had a verbal confrontation afterward in the cage.

The animosity between the two men stems from Du Plessis, a South Africa native, saying he would be the first "real" African champion in a previous postfight interview. Du Plessis' reasoning was that Adesanya and other former champions born in Africa, Kamaru Usman and Francis Ngannou, left the continent and live elsewhere, whereas Du Plessis still lives in South Africa. Adesanya has taken umbrage with those views.

Du Plessis was the preferred opponent for Adesanya at UFC 293 by all parties, but Du Plessis has a foot injury -- one he went into the Whittaker fight with -- and won't be ready by Sept. 9, sources said. The UFC wanted Adesanya-Du Plessis at a later date, sources said, but Adesanya said publicly he wished to remain on the card close to home. Strickland was then tabbed as the foe, and that has been the plan for several weeks. The announcement had been held up because the UFC needed to get Strickland's travel documents in order, according to sources.

Adesanya (24-2), a two-time UFC middleweight champion, is coming off a second-round knockout of Alex Pereira at UFC 287 in April. Pereira beat Adesanya via TKO to win the middleweight belt in November at UFC 281. Adesanya, 34, has five successful middleweight title defenses, second in UFC history to Anderson Silva (10).

Strickland (27-5) has won two straight following a two-fight losing streak. The Las Vegas resident is coming off a second-round TKO of Abus Magomedov on July 1. Strickland, 32, has won seven of his past nine fights since moving up to middleweight in 2020.