Fourth-seeded Romanian Irina-Camelia Begu 6 (7-3), 3-6, 6-4 at the $220,000 Mexican Open tennis event on Monday.
Bacsinszky put Begu to the test, taking the Romanian to a third and final set in a match that lasted just over three hours, but Begu came away with the victory.
Eighth-seeded Italian Alberta Brianti was tested in her first-round matchup with Alize Cornet of France. Cornet, a 2008 runner-up at this tournament, took the first set, but dropped the final two, as Brianti earned a 3-6, 6-3, 6-3 victory on the red clay at The Fairmont Acapulco Princess.
In other opening-round action, Hungarian lefty Melinda Czink bested Canadian Stephanie Dubois 7-6 (8-6), 6-3, Stephanie Foretz Gacon of France outlasted compatriot Mathilde Johansson 6-4, 7-6 (7-5), and Mexican Ximena Hermoso defeated Austria's Patricia Mayr-Achleitner 7-5, 6-3.
This week's top seeds are all Italians -- Roberta Vinci, Flavia Pennetta and Sara Errani. The Mexican Open stalwart that is Pennetta was the champion here in 2005 and 2008 and runner-up in 2004, 2006, 2007 and 2009. She's appeared in six of the last eight finals.
The newest champion here will collect $37,000.