Spain, winners of three of the past five Davis Cup titles, face a must-win doubles on Saturday after Canada took a 2-0 lead over the injury-depleted Spanish in their World Group first-round tie on Friday.
Spain haven't lost in the first round of the nations tournament since 2006, when they fell 4-1 to Belarus.
They were beaten in last year's final by the Czech Republic, but opened their 2013 campaign without their four top players -- David Ferrer, Rafael Nadal, Nicolas Almagro and Fernando Verdasco.
Nadal has been sidelined since June by a left knee injury and then a stomach complaint. Almagro pulled out last week with a leg injury and Ferrer and Verdasco opted out of the tie.
Canadian veteran Frank Dancevic, ranked 166th in the world, stormed to a 6-1, 6-2, 6-2 victory over Marcel Granollers, ranked 34th, to put the hosts up 2-0.
Canada's world number 15 Milos Raonic had opened the tie with a 6-7 (5/7), 6-4, 6-4, 6-4 win over Albert Ramos -- the world number 51 who was making his Davis Cup debut.
Raonic fired 26 aces and 14 service winners as he improved to 7-3 in Davis Cup singles play.
Granollers will try to bounce back on Saturday, when he was scheduled to team with Marc Lopez in doubles against Daniel Nestor and Vasek Pospisil.
Granollers and Lopez won the doubles title at the ATP World Tour finals last November and reached the Australian Open semi-finals in January.
Spain must win the doubles to stay alive in the best-of-five match tie. Spain have won lifted the Davis Cup five times in total, including back-to-back titles in 2008 and 2009 and in 2011. They also won in 2000 and 2004.
Canada, in contrast, are trying to reach the World Group quarter-finals for the first time.