Fellow Canadian Milos Raonic joined her, but his road to the second week at Roland Garros was more gruelling.
Raonic battled to win the fourth five-set match of his career Friday as he overcame crowd favourite Gilles Simon 4-6, 6-3, 2-6, 6-2, 7-5 to become the first Canadian men's singles player to advance past the third round in Paris.
Earlier, Bouchard recovered from early breaks in both sets as she beat Swede Johanna Larsson 7-5, 6-4.
Raonic, the men's No. 8 seed from Thornhill, Ont., needed more than three hours to beat France's Simon. After the match Raonic called the win one of the biggest of his career.
"This win is definitely up there," he said. "It's a new territory I'm putting myself in at this tournament, because I was able to fight and get through in important moments and give myself an opportunity to win.
"There's still a lot more work to do, but it's a good thing. But I'm not really overly excited about it. There is a lot more I want to do, so I'm just really focused in the moment."
Raonic fired 19 aces but rode a roller coaster as he was broken while serving for victory.
But the 23-year-old then broke Simon to go up 6-5, and earned the victory in the ensuing game when Simon hit a long return on match point.
Raonic advanced with 60 winners and six of 12 break points converted, but also committed 74 unforced errors.
"It was just incredible to play a tough opponent like Gilles, I'm very content with this win," said Raonic. "We were on court a long time and I'm a bit tired. When I was broken serving for it, I just told myself I had to break back and go from there. I stayed calm.
"This is my first fourth round here and it's a very important win for me. It's also my first in a big showcourt like this at a Grand Slam. It's all super for me, I want to continue."
The 18th-seeded Bouchard, an Australian Open semifinalist earlier this year, showed fighting spirit in winning her 84-minute match with the 99th-ranked Larsson in the pair's first meeting.
"I started a little slow, I was just a bit rusty on the court," said Bouchard. "But I didn't worry or anything on the court.
"I still had a lot of confidence in myself just to get my groove, and after a few games I started playing much better and really got into the match. The whole match I felt very comfortable and confident.
"(Larsson) plays well, and especially on clay. So it was it was definitely tough."
She is the first Canadian woman since Aleksandra Wozniak to get this far in Paris.
Bouchard finished with 27 winners and 30 unforced errors, breaking on six of 11 chances while losing serve four times.
Montreal's Bouchard lost the opening game but recovered nicely to take a 5-3 first-set lead. She got into trouble as Larsson levelled for 5-all but claimed the set with a break for 7-5 on her third set point.
The Canadian lost serve in the third game of the second, breaking back in the fourth to tie the set at 2.
Bouchard earned a 4-2 lead as she move on to victory, with Larsson donating a double-fault for a second match point before volleying a forehand return low into the net.
Next up for Bouchard is German eighth seed Angelique Kerber, who beat Daniela Hantuchova 7-5, 6-3.
"I'm just trying to enjoy every moment, believe in myself, and I know that I have a chance," Bouchard said. "Every time I walk on the court I have a chance to win.
"It's going to be important to try to start strong in my next match, no matter what."
In mixed doubles, Toronto's Daniel Nestor and French partner Kristina Mladenovic opened with a 6-7 (1), 6-4 defeat of Max Mirnyi of Belarus - a former Nestor men's doubles partner - and Taiwan's KC Chan.
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