Fresh off winning the 1954 Heisman Trophy at Wisconsin, Alan "The Horse" Ameche arrived in Baltimore as the third overall pick in the 1955 NFL Draft and immediately established himself as a dominant focal point for the Colts. Combining a power-packed 218-pound frame with elite speed, he burst onto the professional scene by rushing for 194 yards in his very first career game against the Chicago Bears, featuring a staggering 79-yard touchdown run. Ameche capped his stellar debut campaign by winning the NFL rushing crown with 961 yards and a league-leading nine rushing touchdowns, sweeping Rookie of the Year honors and earning a First-Team AP All-Pro selection.

Ameche served as the ideal backfield anchor for head coach Weeb Ewbank and quarterback Johnny Unitas, delivering punishing runs between the tackles while absorbing heavy workloads. He earned Pro Bowl selections in each of his first four seasons (1955–1958) and added three Second-Team AP All-Pro selections (1956, 1958, 1959). His peak seasons provided the physical backbone for Baltimore's offensive explosion: in 1956, he eclipsed 1,000 yards from scrimmage and racked up nine touchdowns, following that up in 1958 with a dominant 791-yard, eight-touchdown effort on the ground. His career became forever etched in gridiron lore during the 1958 NFL Championship Game against the New York Giants—widely remembered as "The Greatest Game Ever Played". In sudden-death overtime, Ameche capped a grueling drive with a legendary one-yard touchdown dive into the end zone, securing Baltimore's first world championship.

He remained a vital weapon the following season as the Colts captured back-to-back titles in 1959, powering through defenses for 679 rushing yards and five scores while opening up passing lanes for Unitas and Raymond Berry. Tragically, Ameche’s stellar trajectory was cut short during his sixth season in 1960 when he suffered a severe Achilles tendon injury that forced him to retire at just 27 years old. Despite his brief career, his impact across the decade earned him a selection to the NFL 1950s All-Decade Team.

Overall, Ameche amassed 4,045 rushing yards, 40 rushing touchdowns, 101 receptions, 733 receiving yards, and four receiving touchdowns.