 Mendis scored over 21,000 runs in his first-class career.As a youngster, Mendis represented the Sussex Young Cricketers, England Schools Cricket Association, and National Association of Young Cricketers teams, and in 1974, Mendis played for Bede College as they won the British Colleges National Knockout Cup.He made his first-class debut for Sussex in a 1974 County Championship match against Worcestershire at the Central Recreation Ground, Hastings.