Davydenko wore down the hard-serving Ivo Karlovic for a 6-7 (5-7), 7-6 (8-6), 6-0 victory. After winning the last three points of the second-set tiebreaker, Davydenko turned around and controlled the third set. He lost only nine points -- three on serve -- in the set.
Each player had a break in the first set and Davydenko saved five break points to keep in the second set.
Top-seeded Jo-Wilfried Tsonga, the tournament defending champion, fell behind early against Jesse Levine but won the last five games of the first set and didn't face a break point in the second of a 6-3, 6-4 win.
Seventh-seeded Gael Monfils knocked off No. 2-seeded Philipp Kohlschreiber 6-7 (3-7), 6-4, 6-4 in a 2 1/2-hour match. Monfils improved to 7-1 lifetime against the higher-rated Kohlschreiber with two breaks in each set.
Fifth-seeded Andreas Seppi took out No. 4-seeded Florian Mayer 7-5, 6-2 in 61 minutes. Seppi was broken once but still dropped just 12 points over 10 serving games.
Tsonga will go against Davydenko in the semifinal Saturday while Seppi plays Monfils.