Ljubicic won his rain-delayed second-round match against Swiss wild card Marco Chiudinelli, 6-7 (6-8), 6-3, 6-2, on Friday -- but then lost his second match of the day to sixth-seeded Feliciano Lopez, who also had play in two matches Friday.
Lopez came back from a set down to oust countryman Ruben Ramirez Hidalgo, 6-7 (5-7), 6-3, 7-6 (7-3), and will play unseeded Marin Cilic of Croatia in Saturday's semifinals.
Cilic beat Dusan Vernic of Serbia and Romania's Andrei Pavel in two three-set matches played on Friday.
Gaudio, the event's defending champion, lost to France's Richard Gasquet, 6-3, 6-2. Unseeded German Philipp Kohlschreiber ousted third-seeded Spaniard Fernando Verdasco, 6-3, 4-6, 6-4, to face the 20-year-old Gasquet in the semis on Saturday.