It took world No. 18 Bouchard two hours seven minutes to beat No. 137 Kristina Kucova in three sets 7-6 (0), 2-6, 6-1.
"I didn't play well today. I am proud the way I fought through it" said Bouchard after the match.
The Montreal native started very slowly, not being able to find her rhythm, committing unforced errors and double faulting on important points.
"Lack of consistency was a big issue for me today" she added.
Down 0-3 in the opening set, Bouchard started winning some key rallies, and after tying the set 6-6 she won seven points in a row in the tiebreaker to take the first set 7-6.
But Kucova, who never finished a season being ranked inside the WTA's Top 100, played with even more determination. Hitting winners off both sides with her two-handed groundstrokes she won the second set quickly and decisively.
"I know I can play well against top players," said Kucova. "This year I've already play 3 set matches against Flavia (Pennetta) and Alize (Cornet). I've lost, but I know I can play at their level."
Bouchard then centred herself and cruised to a 6-1 win in the final set.
Earlier, Aleksandra Wozniak earned a 4-6, 7-5, 7-5 win over Jana Cepelova in the first match of the tie.
The Blainville, Que., native trailed 2-5 in the second set before she began playing more confidently off the ground, moving her opponent around the court and forcing errors from the young Slovak.
"It was a difficult match," said Wozniak. "We've never played before so I was focusing on reading her game, and this is why I was missing so much in the beginning of the match"
Cepelova, ranked almost 100 spots higher than Wozniak, twice served for the match in the second and third sets but couldn't finish off the win.
"I wanted to win this match so much! I've been here for 12 days waiting for today," said Wozniak. "It was so close, and I thought I've already won this match"
Canada can secure a spot in the World Group I for 2015 in the first reverse singles match, when Bouchard plays Cepelova.
The Canadians only need to win one match on Sunday to beat Slovakia for a place in the elite World Group. "But I have to play much better than today. Have to find my consistency before tomorrow's match " said Bouchard.
After the first match between Bouchard and Cepelova, Wozniak will face Kucova, and in doubles competition Toronto's Sharon Fichman and Ottawa's Gabriela Dabrowski will play Janette Husarova and Cepelova.