The Frenchman, who had extra time to prepare after quarter-final opponent Tomas Berdych withdrew through illness on Friday, converted his only break opportunity in the fifth game on his way to taking the opening set.

Ljubicic, twice a beaten finalist in Rotterdam, improved his return game in the second and secured an early break, but the Croatian handed the advantage back when serving for the set and Tsonga clinched the match in the tiebreak.

"The big difference today was in serving as he (Ljubicic) didn't serve like he normally does and also my extra day rest, while Ivan played three sets was an advantage," Tsonga told reporters.

"It was my first win in an important match for a long time and that gives me confidence."

Tsonga will face either top seed and holder Robin Soderling or Victor Troicki in Sunday's final.