Joe Salisbury earned victory over Jamie Murray as the only two Britons involved in the ATP Finals went head-to-head in their opening doubles group match.
Salisbury and American partner Rajeev Ram won 6-1 7-6 (7-5) against Murray and Brazil's Bruno Soares in Turin.
US Open champions Salisbury and Ram are second seeds at the year-ending finals.
In the singles, Novak Djokovic plays his opener against Norwegian debutant Casper Ruud later on Monday as he aims for a record-equalling sixth title.
Serbian top seed Djokovic, 34, has not won the event since 2015.