Gulbis fired 11 aces and won 84 percent of his first-serve points en route to a 7-6 (7-3), 6-4 win over eighth-seeded Mario Ancic. Gulbis won nearly half of the points on first serves from Ancic and that was the difference in the hard-court match.
Also Monday, Carlos Moya took a 6-1, 4-6, 6-4 win from Albert Montanes, Janko Tipsarevic defeated Jeremy Chardy 7-6 (7-5), 7-5 and Jose Acasuso beat Guillermo Canas 6-3, 2-6, 6-3.
The tournament runs through Sunday when the champion will take home $85,000.
LGBT community has 'bullied the American people': Bachmann
Ohio bar shooting arrested, charged with murder