The UFC needs a new headliner for its upcoming event on April 17 after Paulo Costa has decided to withdraw from a middleweight clash with Robert Whittaker, multiple people with knowledge of the situation told MMA Fighting.

Costa is dealing with a severe flu and can’t fully prepare for the pivotal fight, according to those people. It’s still unclear if the promotion will move the matchup to a new date or find a new opponent for ex-champion Whittaker. One option currently on the table is rescheduling the match for UFC cards on May 1 or May 8.

Ag. Fight first reported the bout was in jeopardy on Monday night.

Costa (13-1) is coming off a one-sided defeat to middleweight champion Israel Adesanya in September 2020, suffering the first loss of his professional MMA career. “Borrachinha” was 5-0 inside the octagon going into UFC 253, including wins over Yoel Romero and Uriah Hall.

Whittaker (22-5) ascended to the top of the 185-pound class with key wins over the likes of Ronaldo Souza and Yoel Romero before losing the UFC belt to Adesanya in 2019. “The Reaper” has since bounced back with a pair or decision wins in 2020, defeating Darren Till and Jared Cannonier.