The UFC says No.1 contender Ferguson will fight Gaethje for the interim lightweight title in the main event of UFC 249, at a yet to be determined location.

The mixed martial arts promotion announced the main event match-up on Monday.

Gaethje comes in as cover for the unbeaten Nurmagomedov, who is apparently unable to leave Russia during the coronavirus pandemic.

Although UFC President Dana White still hasn't even announced a venue for UFC 249, he remains determined to hold a pay-per-view show this month.

White wrote on Twitter: "The fight is signed and is 100% ON LIVE on ESPN somewhere on EARTH!!!!"

Most US states have restrictions in place that would make it impossible to stage a show, even without an audience.

UFC 249 initially was slated for Brooklyn, but a venue change became necessary several weeks ago.

ESPN, the UFC's broadcast partner, has said White is attempting to secure an unnamed venue on the west coast for the show.

The UFC held a full fight card in an empty arena in Brazil last month but cancelled its ensuing three scheduled shows.

White has remained steadfast in his plan to stage the company's biggest show of the spring while virtually all high-level sports competition has stopped.

Ferguson (25-3) is a longtime lightweight contender who has been booked to fight Nurmagomedov five times, with each bout falling through due to injury or other circumstances.

Gaethje (20-2) is among the UFC's most exciting fighters.

"I'm terrified and I ... love it," Gaethje tweeted after the announcement of his fight.

Nurmagomedov announced last week that he wasn't planning to leave his native Dagestan, suggesting Russia's travel restrictions made it impossible.

He later claimed he would be willing to leave for the fight but couldn't plan because he didn't know where or when it would occur.

Australian Associated Press