UFC 266: Volkanovski vs. Ortega was a mixed martial arts event produced by the Ultimate Fighting Championship that took place on September 25, 2021, at the T-Mobile Arena in Paradise, Nevada, part of the Las Vegas Metropolitan Area, United States.

[2] After a one-year hiatus due to the COVID-19 pandemic, the promotion announced the return of 'International Fight Week', which took place in Las Vegas during the days leading up to and surrounding the event.

[5] A UFC Featherweight Championship bout between current champion Alexander Volkanovski and former title challenger Brian Ortega headlined the event.

[17] The pairing was previously scheduled for UFC on ESPN: Rodriguez vs. Waterson in May, but Modafferi pulled out due to a meniscus tear a month before that event and the bout was scrapped.

[19] However, the bout was never officially announced by the promotion and Valiev was instead scheduled to face Daniel Santos at UFC Fight Night: Ladd vs.