The Fourth's Battle to the Death!! (四代目の死闘!!, Yondaime no Shitō!!) is chapter 502 of the Naruto manga.
As Tobi moves towards Konoha, several people felt the Nine-Tails' presence, including Kakashi, the Third Hokage, and Itachi. Tobi then summons the fox causing chaos. The Third organises Konoha to battle the fox, while wondering how Kushina's seal broke, despite all the precautions. Minato enters Konoha, on Hokage Monument, causing the Nine-Tails to sense him and fire a Tailed Beast Ball at him. Minato counters the blast with Flying Thunder God: Guiding Thunder sending the blast behind Konoha, alerting the village of his presence. Minato is ambushed by Tobi, who tries to send Minato away. Using the Flying Thunder God Technique Minato quickly escapes, but Tobi follows after him. Realising that Tobi's strength and knowledge is too abnormal, Minato questions if Tobi is truly Madara Uchiha, but states it is impossible, as Madara Uchiha is dead. Tobi speculates on the matter. Minato concludes that with a technique superior to his own and his ability to control the Nine-Tails, Tobi is too dangerous to be left alive. The battle comes down to speed. They charge towards each other, Minato throwing a Flying Thunder God Kunai only to have Tobi phase through it. He then forms a Rasengan. Tobi grabs Minato's shirt, thinking he has won, only to have Minato disappear and reappear over Tobi striking him with the Rasengan.