UFC Fight Night 231: Almeida vs. Lewis was a mixed martial arts event produced by the Ultimate Fighting Championship that took place on November 4, 2023, at Ginásio do Ibirapuera in São Paulo, Brazil. The event was expected to be headlined by a heavyweight bout between Curtis Blaydes and Jailton Almeida. However, Blaydes withdrew for unknown reasons and was replaced by former UFC Heavyweight Championship challenger Derrick Lewis.