Sources: Kelvin Gastelum to replace Paulo Costa, fight Robert Whittaker on April 17

One of the most notable UFC title fights to have ever been canceled has a new date.

Former middleweight champion Robert Whittaker (22-5) will face Kelvin Gastelum (17-6) in a five-round main event at UFC Fight Night on April 17 in Las Vegas, multiple sources told ESPN. Gastelum has agreed to replace Whittaker's original opponent, Paulo Costa, who withdrew this week because of illness.

Whittaker and Gastelum were scheduled to fight when Whittaker was still champion in February 2019, in Whittaker's home country of Australia. The 185-pound championship was canceled the morning of the event, however, when Whittaker was hospitalized and underwent emergency surgery for a collapsed bowel and internal hernia.

Gastelum went on to face now-champion Israel Adesanya for an interim title, and lost via unanimous decision. Adesanya unified the belts in a win over Whittaker in October 2019.

Whittaker is coming off a terrific 2020 campaign in which he recorded wins over Darren Till and Jared Cannonier. Gastelum, meanwhile, endured the worst skid of his career after missing out on the Whittaker title fight, losing to Adesanya, Till and Jack Hermansson. The 29-year-old looked great in a comeback win last month against Ian Heinisch.

Adesanya remains the middleweight champion, coming off a failed bid to become a two-weight champion against light heavyweight king Jan Blachowicz on March 6. Adesanya has already stated he intends to return to 185 pounds and defend his title in his next appearance.