Dragon League (TV Series, 39 episodes, AniDB)

Requested on March 11, 2021, 2:57 p.m.

Tokio and his father Amon go to the soccer country of Elevenia where they see a parade of the strongest soccer team of that country, the Winners. Amon challenges the team captain Leon to a soccer battle and, when Amon loses, Leon turns him into a miniature dragon. Tokio sees the fight and decides to challenge against Leon so that Amon can become human again. Source: AnimeNfo