Welcome to the UFC, JooSang Yoo.

The featherweight prospect earned a devastating knockout victory in his Octagon debut, face planting Jeka Saragih with a left hook 28 seconds into their fight Saturday at UFC 316 in Newark.

Yoo - known as "Zombie Jr." - is now 9-0 as a professional. The 31-year-old South Korean owns four victories by knockout.