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 won his opening match against Norwegian debutant Casper Ruud as he aims for a record-equalling sixth title.
Serbian top seed Djokovic, who has not won the event since 2015, recovered from losing serve in the first game to win 7-6 (7-4) 6-2.
But there was a defeat for 2019 champion Stefanos Tsitsipas, with the Greek beaten 6-4 6-4 by Russian fifth seed Andrey Rublev.
Meanwhile, Italy’s Matteo Berrettini is set to make a late call on whether he is fit to face Hubert Hurkacz on Tuesday after an abdominal injury forced him to retire from his opener against Alexander Zverev on Sunday.
He posted on Instagram on Monday that it had been “one of the toughest experiences” of his career and that his team was “still evaluating everything following multiple scans and assessments today”.
Should he withdraw from the tournament, fellow Italian Jannik Sinner would take his place as the first alternate. Britain’s Cameron Norrie is the second alternate.
In the women’s equivalent of the season-ending tournament for the year’s eight leading players, all eyes will be on the final group match between Belarusian top seed Aryna Sabalenka and Greece’s Maria Sakkari (01:30 GMT Tuesday), with the winner taking the last remaining semi-final spot.
Already through in Guadalajara, Mexico, are Spaniards Garbine Muguruza and Paula Badosa, and Estonia’s Anett Kontaveit.
