Jamie Murray and Dom Inglot put Great Britain 2-1 up against Canada with victory in Saturday's Davis Cup doubles contest in Ottawa.
The British pair beat Daniel Nestor and Vasek Pospisil 7-6 (7-1) 6-7 (3-7) 7-6 (7-3) 6-3 to edge the visitors ahead in the best-of-five World Group tie.
Dan Evans will play Pospisil in Sunday's fourth rubber, before Kyle Edmund faces Denis Shapovalov.
The winners of the tie will travel to France for the quarter-finals in April.
Both Britain and Canada are without their leading players, as world number one Andy Murray recuperates after the Australian Open and number four Milos Raonic is injured.