UFC featherweight champion Max Holloway has been forced to withdraw from UFC 226 just days before the card.

"Max's team and UFC staff noticed Max was not normal since late last week," Holloway's manager Brian Butler told ESPN via a prepared statement. "This became obvious to many watching his interviews and public appearances the past few days.

"He was showing concussion-like symptoms before he even started his weight cut and was rushed to the ER on Monday where they admitted him overnight. Initial scans seemed OK, and he was released Tuesday afternoon, but symptoms still continued.

Max Holloway, left, is out of his UFC featherweight title fight. Josh Hedges/Zuffa LLC/Getty Images

"Max fought with his team to continue with the fight. He showed some improvement over the next day but was still showing obvious symptoms. After open workouts, he crashed and was very hard to wake up; when he did, he had flashing vision and slurred speech.

"He is now back in the ER for further tests."

Holloway was scheduled to fight Brian Ortega in the co-main event of UFC 226 this Saturday night in Las Vegas.

"Stepping into the co-main position is another highly-anticipated heavyweight bout featuring No. 1 ranked Francis Ngannou and No. 5 ranked Derrick Lewis," the UFC said in a statement on Thursday. "The bout featuring Paul Felder and Mike Perry will move to the main card."

UFC president Dana White told ESPN that the promotion tried to book a last-minute interim title fight between Ortega and Jeremy Stephens. Ortega declined the proposed matchup, in favor of waiting to re-book his official title fight against Holloway.

This marks the second time in a row Holloway has been forced to withdraw from a bout during fight week. He was ruled medically unfit to fight a day before UFC 223 in April due to trouble cutting weight.

Holloway also pulled out of UFC 222 due to an injured ankle a month before the event.

ESPN's Brett Okamoto contributed to this report.