Sirola's best result in a Grand Slam singles event was at Roland Garros in 1960, where he beat #1 seed, Barry MacKay in the Quarterfinals to reach the Semifinals. He also won the Roland Garros doubles title in 1959, partnering Nicola Pietrangeli. He was a member of the Italian teams which finished runners-up to Australia in the Davis Cup in 1960 and 1961.