Roger Federer is on course for his eighth title at the Gerry Weber Open in Halle after edging past Ivo Karlovic in the semi-finals.
The world number two held serve throughout, but was taken to two tie-breakers by the big-serving Croatian during the 7-6(3) 7-6(4) victory.
Federer took the first set after making a breakthrough with a powerful backhand return before Karlovic succumbed to a double fault.
He won the second tie-breaker by claiming two points on the Croatian's serve and sealing the match with a backhand volley.
The Swiss will meet either Italy's Andreas Seppi or second seed Kei Nishikori in the final.
