ONE 166: Qatar was a combat sport event produced by ONE Championship that took place on March 1, 2024, at Lusail Sports Arena in Lusail, Qatar. A ONE Middleweight World Championship bout between current champion Reinier de Ridder (also former ONE Light Heavyweight World Champion) and the ONE Light Heavyweight and Heavyweight Champion Anatoly Malykhin headlined the event.

Andy Ruiz Jr. vs. Anthony Joshua II, billed as Clash On The Dunes, was a heavyweight professional boxing rematch between the Mexican-American champion Andy Ruiz Jr. and British former champion Anthony Joshua, for the unified WBA, IBF, WBO and IBO heavyweight world titles.