The Angry Super Saiyan! Goku Throws Down the Gauntlet! (怒りの超サイヤ人！悟空リングの息子に帽子を投げる！, The Angry Super Saiyan! Throw Your Hat in the Ring Son Goku!) is the forty-eighth episode of Dragon Ball Z Kai. It first aired in Japan on March 14, 2010. Its American air date was November 27, 2010.
The transformed Goku renews his battle with Frieza, and significantly outclasses the tyrant. Frieza launches several counterattacks at Goku, but they have no effect at all. As Frieza stares at his opponent, he realizes that his worst nightmare has come true; Goku is a Super Saiyan. In an attempt to defeat Goku, Frieza creates a Death Ball and hurls it into Namek's core, planning to destroy the planet.
This episode marks the first time that Goku's full name, Son Goku, is outright stated in an English dub.