Dan Evans saw off Canada's 17-year-old Denis Shapovalov in straight sets to win his first match as Great Britain's Davis Cup number one.
The world number 45 won 6-3 6-3 6-4 to give the visitors an early lead in the best-of-five World Group first-round tie in Ottawa.
Evans, 26, is the highest-ranked player in the absence of world number one Andy Murray and number four Milos Raonic.
Kyle Edmund takes on Vasek Pospisil in Friday's second singles match.
Jamie Murray and Dom Inglot are scheduled to face Daniel Nestor and Pospisil in Saturday's doubles contest, before the reverse singles on Sunday.