If you want to skip world 5, then in world 4, in level 2, there are actually 2 warp zones. in the first opening on the brick ceiling hit some blocks and a vine will grow up. climb it and you will find warp zones for worlds 6, 7 & 8. of you want to go to the second warp zone in this level, stay on top of the ceiling and go to the end and you will find world's 5, 6 &7!!!!!!!:)