Considered to be one of the best players of his generation, as well as one of the greatest strikers of all time, Riva enjoyed a remarkable scoring record for Cagliari, thanks to his composure in front of goal, powerful left foot and aerial ability; his speed, strength and eye for goal led the Italian journalist Gianni Brera to nickname him "Rombo di Tuono" (Roar of Thunder). Aside from his debut season with Legnano, Riva remained with the Sardinian club for his entire career: he helped Cagliari achieve promotion to the Italian top-flight for the first time in 1964, and later led the club to their only Serie A title in 1969–70.