Cosell rose to prominence covering boxer Muhammad Ali, starting when he still fought under his birth name, Cassius Clay. The two seemed to be friends, despite their very different personalities, and complimented each other in broadcasts.
In 1970, ABC executive Roone Arledge hired Cosell to be a commentator for a Monday Night Football, the first time that football was broadcast in prime time. Cosell was accompanied most of the time by ex-football players Frank Gifford and Don Meredith.
Cosell denounced professional boxing in 1982 after a brutal fight between Larry Holmes and Randall Cobb, and left Monday Night Football in 1983, calling football "a bore." He hosted a program called Sportsbeat for a few years and had a short-run variety program called Saturday Night Live with Howard Cosell, but never achieved such fame again.