Superman vs Muhammad Ali (1978)

Summary

In 1978, an alien race called the Scrubb demands that Earth''s greatest champion battle their world''s own greatest fighter. Both Superman and Muhammad Ali step forward — and to determine who is truly Earth''s greatest fighter, Superman temporarily loses his powers and faces Ali in the ring. Ultimately, the duo must work together to defeat the Scrubb, with Ali taking on their champion while Superman battles their space-armada.