Day became the first team goalkeeper soon after. In 1975, aged 19 he became the youngest goalkeeper ever to appear in an FA Cup Final, in their victory over Fulham. He received the PFA Young Player of the Year Award that same season, the only goalkeeper to have won the award. He was tipped as the next great England goalkeeper. In 1976, he appeared in the Cup Winners' Cup Final which West Ham lost 4–2 to Anderlecht at a sold out Heysel Stadium. However, a loss of form and injuries saw him drop out of the side, and Phil Parkes' performances were good enough to keep Day out when he regained fitness.