In 1991, he won a European Cup Winners' Cup medal with United, and in 1990 he won the FA Cup with them. He was United's regular left-back in the 1990–91 season, but when Paul Parker signed in the close season, Denis Irwin was switched to left-back and Blackmore returned to his familiar pattern of alternating between different positions, although he did enjoy a good run at right-back when Parker was injured.