The highly anticipated return of Khamzat Chimaev will have to wait.

The undefeated fighter was set to headline the UFC’s first event in Saudi Arabia on June 22 against former champion Robert Whittaker. However, UFC president Dana White announced Thursday that Chimaev has been pulled from the main event of UFC on ABC 6 because he has been “violently ill.”

Chimaev will be replaced by Ikram Aliskerov (15-1 MMA, 2-0 UFC), who was slated to face Antonio Trocoli in the co-main event of Saturday’s UFC Fight Night event at the UFC Apex.

The removal of Chimaev comes during a time when the promotion is dealing with a fair bit of turmoil in what was supposed to be a star-studded series of events. The status of the main event of UFC 303 on June 29 has been shrouded in doubt, as the status of Conor McGregor is up in the air. The former two-division champion was scheduled to return from a three-year hiatus to face Michael Chandler. But after the abrupt cancellation of a news conference in McGregor’s home country of Ireland to promote the fight, there have been questions about McGregor’s health and ability to compete.

The loss of Chimaev put yet another main event in turmoil, as the promotion scrambled to put the pieces back together on a little over a week’s notice. However, the UFC didn’t have to look far, as Aliskerov, who has only lost to Chimaev in his MMA career, answered the call. Aliskerov gets a massive bump in competition in his third UFC bout, going from facing an unranked middleweight to the former 185-pound champion. In Aliskerov’s last outing in October, he stopped Warlley Alves in the first round.

As for Chimaev, his availability to compete has been an issue over the past couple of years after his meteoric rise following his 2020 debut. He has competed only once since submitting Kevin Holland in September 2022, with a majority decision win over former welterweight champion Kamaru Usman in October. Also in October, one of Chimaev’s coaches revealed that visa difficulties because of his Chechen nationality and Russian passport have prevented “Borz” from competing in the United States, leaving the UFC to find international fight cards for the 30-year-old.

The Saudi Arabia card was thought to be the perfect event for Chimaev to make his return in what was likely a middleweight title eliminator against Whittaker. However, a photo from one of his sparring partners showed Chimaev in bed with an unknown illness. White emphasized that Chimaev was “violently ill” and wished him a return to good health.