Astro Boy: Tetsuwan Atom - episode 2 - 12 Apr, 2003

Harley, a Robot Ball player, is a popular player known for his fair play. However, Harley and the rest of the Omega Knights led by him suddenly turn into violent players who ignore the rules. They are actually being manipulated by Dr. Tenma, whose goal is to show the audience an ugly fight between robots. The fighters engage in a horrible battle full of foul play and that turns the audience away. Harley then turns to Atom and demands a fight. (Source: Wikipedia)