Gulbis suffered two service breaks in the first set but came away a 4-6, 6-1, 6-1 winner over Marcel Granollers. Gulbis dropped a total of 20 points serving n the second and third sets.
He heads into the second round against Haas, who like the other top-four seeds, had a first-round bye.
Thomaz Bellucci ousted second-seeded Lukas Rosol 6-4, 6-4, saving all six of the break points he faced. No. 5-seeded Fabio Fognini got past Alexander Ward 6-3, 7-6 (7-5) while wining 70 percent of the points on serve and sixth-seeded Florian Mayer edged Andreas Beck 6-4, 3-6, 6-1.
Leonardo Mayer outlasted Pablo Andujar 3-6, 7-6 (7-5), 7-6 (7-5) in a match that took nearly 3 hours.
Victor Hanescu came from behind to eliminate Dmitry Tursunov 3-6, 6-3, 7-6 (9-7); Nikolay Davydenko defeated Daniel Munoz-de la Nava 6-7 (6-8), 6-3, 6-4; Gael Monfils advanced over Paul-Henri Mathieu 7-6 (7-0), 6-4; and Nils Langer beat Robin Kern 3-6, 6-4, 6-3.
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