In chapter 55 in the manga, equally Goku and Vegeta have their respective new coaching regiments interrupted by the specter of evil sorcerer Moro, that's on his approach to annihilate the Earth. In the case of Vegeta, the Saiyan Prince has to struggle among Moro's henchmen on World Yardrat - http://mylesremua.pages10.com/The-smart-Trick-of-dragon-ball-super-2020-That-No-One-is-Discussing-30525930