Britain's Joe Salisbury and American partner Rajeev Ram brushed aside a lack of practice to get their ATP Finals campaign off to a winning start.
They had been unable to train together in the build-up because Salisbury was self-isolating for two weeks after his coach tested positive for Covid-19.
But there was little sign of rustiness in a 7-5 3-6 10-5 win over Lukasz Kubot and Marcelo Melo in their opening round-robin match at London's O2 Arena.
Salisbury is the only Briton competing.
He and Ram took the opening set against Poland's Kubot and Brazil's Melo with Ram's fantastic forehand service return but then paid the price for a drop in serving percentages to allow their opponents to level and take it to a match tie-break.