Former middleweight title challenger Paulo Costa withdrew from his Aug. 21 main event against Jared Cannonier, sources told ESPN's Brett Okamoto.
Kelvin Gastelum reportedly agreed to step in for Costa.
Gastelum's last fight was also as a replacement for Costa, who pulled out of his April 17 main event versus Robert Whittaker due to an illness. Whittaker beat Gastelum via unanimous decision.
Cannonier, the No. 4-ranked middleweight, is coming off a loss to Whittaker in October that snapped his three-fight winning streak. The 37-year-old has a 6-5 record since entering the UFC in 2015.
Meanwhile, the No. 9-ranked Gastelum has lost four of his last five fights, including defeats to 185-pound champion Israel Adesanya and Darren Till.
Adesanya is set to defend his title in a rematch with Marvin Vettori at UFC 263 on June 12. The winner is widely expected to face Whittaker, who is 3-0 since dropping his belt to Adesanya in 2019.