Halle - Ivo Karlovic fired a remarkable 45 aces and upset third-seeded Tomas Berdych 7-5, 6-7 (10/8), 6-3 to advance to the Gerry Weber Open semi-finals on Friday.
Karlovic made the first break at 5-5 following a Berdych double fault.
The eighth-seeded Croat fought back to level the second set tiebreaker after Berdych missed three set points, but he missed a match point and hit a return into the net for the Czech to take the set.
Karlovic went 3-1 up in the third, held his serve, and finished the match in 2 hours, 12 minutes with yet another ace.
The 27th-ranked Karlovic will next play either Roger Federer or Germany's Florian Mayer.