Muller set the tone by sending down four aces in the opening game. But Ljubicic quickly caught up and the 2005 champion rallied from 3-2 down in the tiebreaker to take the first set.

Though Muller finished the match with 18 aces, he could not handle Ljubicic’s serve. He sent a backhand volley wide to give Ljubicic a match point which the fourth-seeded Croatian converted with an ace.

Ljubicic will face Frenchman Jo-Wilfried Tsonga or Alexandr Dolgopolov of Ukraine in Sunday’s final.