Mohammed Usman has pulled out of his scheduled fight against Valter Walker at UFC Fight Night 261 in Rio de Janeiro.Usman, who holds an 11-4 professional record, was seeking back-to-back wins after earning a decision victory over Hamdy Abdelwahab earlier this year. His withdrawal has left uncertainty over whether Walker will remain on the card or if the matchup will be rescheduled.For Usman, this is another interruption in what has been a stop-start UFC career. After suffering two consecutive decision losses, the 35-year-old was looking to re-establish momentum in the division.His performance against Abdelwahab in June showed improvements in composure and wrestling control. Meanwhile, Walker, who has surged with a three-fight winning streak, was preparing to leverage the energy of a home crowd to make a statement.Each of his recent victories came by heel hook submission, which, in the eyes of many, makes him one of Brazil’s more promising heavyweight prospects. With Usman out, the spotlight now shifts to how the promotion adjusts the lineup for the Rio card.Who else is fighting on the UFC Rio card?Even with Mohammed Usman out, UFC Rio still promises a night of competitive fights. The spotlight remains on Charles Oliveira, who returns to Brazil for the first time in over five years to face Mateusz Gamrot in the main event.Oliveira is looking to bounce back from a recent knockout loss, while Gamrot, stepping in on short notice, has won four of his last five fights and aims to make a statement in the lightweight division.The co-main event pits former flyweight champion Deiveson Figueiredo against Montel Jackson. Figueiredo is trying to recover after back-to-back losses and injury setbacks. Meanwhile, Jackson comes in on a six-fight winning streak with momentum on his side.In the welterweight division, Vicente Luque faces Joel Alvarez in a fight between two proven finishers. Heavyweights Jhonata Diniz and Mario Pinto square off in a matchup that could push the winner closer to the division’s top fifteen, while featherweights Ricardo Ramos and Kaan Ofli meet in a bout that promises must-watch action.The preliminary card adds depth, featuring Brazilian prospects including Bia Mesquita, Lucas Rocha, and Julia Polastri, all seeking to leave a mark.