Ljubicic, playing in his home country, took more than three-quarters of the points on serve and nearly half when receiving in a 6-2, 6-3 victory over Daniel Brands. He was good on only 51 percent of his first serves but still didn't face a break point.
Qualifier Alex Bogomolov Jr. was even more efficient in defeating No. 7-seeded Philipp Petzschner 6-1, 6-2. The match took just 53 minutes as Bogomolov dropped only 12 points in eight games on serve. Bogomolov's first-round match took nearly three hours.
Ivan Dodig had four service breaks in a 6-2, 6-3 win over Illya Marchenko and fourth-seeded Richard Gasquet advanced in a walkover when Arnaud Clement was unable to play Thursday because of a shoulder injury.
A quarterfinal match pitting top-seeded Marin Cilic and No. 5 Florian Mayer was determined Wednesday. Thursday's results set up the rest of the quarters with Gasquet playing eighth-seeded Michael Berrer, Bogomolov meeting No. 3-seeded Guillermo Garcia-Lopez and Dodig paired against Ljubicic.