Jamie Murray made a winning start to his ATP World Tour Finals debut alongside John Peers, with victory over Simone Bolelli and Fabio Fognini.
Murray and Australian Peers beat the Italian duo 7-6 (7-5) 3-6 11-9 in a dramatic opening match at London's O2.
That gives them an early lead in the round-robin stage, with Bob and Mike Bryan to face Rohan Bopanna and Florian Mergea later on Sunday.
Top seed Novak Djokovic plays Japan's Kei Nishikori in the opening singles.
Six-time champion Roger Federer will take on Czech Tomas Berdych in the evening session at 20:00.