Bouchard, who last year became the first Canadian to reach a Grand Slam singles final at Wimbledon, was beaten by by Yaroslava Shvedova of Kazakhstan 6-4, 1-6, 6-4.
Bouchard reached three consecutive Grand Slam semifinals last year but is going through a difficult season, having lost nine of her past 10 matches, and dropped out of the top-10 rankings. She lost her opening match at the French Open.
In men's play, seventh-seeded Fernando Verdasco defeated Daniel Gimeno-Traver 7-6 (3), 6-7 (6), 6-2 in an all-Spanish first-round match. No. 6 seed Adrian Mannarino of France and No. 8 Joao Sousa of Portugal also advanced.
Verdasco will be up against local favourite Robin Haase for a place in the quarterfinals.