 Mathews' first sizable role was as Lee J. Cobb's son in "The Garment Jungle" (1957).He was promoted to star for "Tarawa Beachhead" (1958), a war film produced by Charles Schneer.Schneer liked the actor's work and cast him in the role of Sinbad in "The 7th Voyage of Sinbad" (1958), directed by Nathan Juran with effects by Ray Harryhausen.