 Complete the following phrase:  Despite his talent and goalscoring prowess, Rivas career was blighted by several major injuries, in particular with the Italian national side, and which greatly limited his playing time in later seasons; he missed 35 games in the five seasons leading up to 1971, and only appeared in 24 matches for Cagliari between 1974 and 1976, which saw an overall decline to his goalscoring rate and the clubs performances during this period. During the 197475 season, a calf injury limited him to 8 appearances and 2 goals with the club, and on 1 February 1976, while playing in a match for Cagliari against Milan, Riva ruptured a tendon and tore an adductor muscle in his right thigh, following a physical shoulder challenge near the corner flag from Aldo Bet, after being chased down by the Milan defender; he never successfully recovered and, despite several comeback attempts over the next year and a half, was eventually forced to retire in 1978, at the age of 33, having played his last game at the age of 31 in 1976. The injury limited Riva to only 15 appearances during the 