Kamaru Usman Fighting Khamzat Chimaev On Short Notice After Costa Pulled

Former UFC champion Kamaru Usman was chillin' last night ... today he's prepping to fight Khamzat Chimaev across the world next week after Paulo Costa was pulled from the fight over an illness.

Costa and Chimaev were co-main event of UFC 294 -- going down October 21 on Fight Island in Abu Dhabi -- until Paulo came down with Staph infection.

The MMA star released a short statement explaining the situation ... "I am hospitalized and had to do a second surgery yesterday. According to doctors, a third surgery will be necessary on Friday. So, I will not be medically cleared to fight on October 21st."

But, have no fear ... Dana White showed he's a miracle worker once again. Just a day after saving the main event when Charles Oliveira was pulled with a laceration on his face (Alex Volkanovski will face Islam Makhachev), the UFC honcho got on the horn with Usman and his manager, Ali Abdelaziz, and we have a fight!

Of course, Usman is a legend, a future Hall of Famer, and one of the best welterweights to ever step foot in a cage. But, he's lost two in a row to champ Leon Edwards.

Before the two fight skid, the Nigerian Nightmare won an astonishing 19 fights in a row. A win over Borz would presumably catapult Usman into the title picture in the welterweight and middleweight divisions.

As for Khamzat, Chimaev is a perfect 12-0 as a pro fighter (6-0 in the UFC) and counts victories over stars Kevin Holland and Gilbert Burns.