Britain's Jamie Murray made a winning start to the ATP Finals when he and Bruno Soares beat Raven Klaasen and Michael Venus in the doubles.
The Scot and his Brazilian partner needed a match tie-break to win their opening round-robin match 7-6 (7-5) 4-6 10-5 in London.
The pair have reached the semi-finals in the past two editions of the event.
The singles starts on Sunday with Kevin Anderson against Dominic Thiem before Roger Federer faces Kei Nishikori.