World 2 is the second world in New Super Mario Bros. with a desert-like theme with enemies such as Pokeys. Like World 1, Bowser Jr. is fought here again for the second time and the main boss here is Mummipokey. This world introduces Warp Pipes which allow Mario and Luigi to skip levels and get closer to the castle. When Mummipokey is defeated as Mini Mario, Mario will be able to advance to World 4 instead of World 3 as when Mummipokey is defeated in any other form, Mario and Luigi will advance to World 3.