BANGKOK, Thailand — Top-seeded Novak Djokovic defeated Robin Soderling 6-4, 7-5 today to advance to the semifinals at the Thailand Open.

Second-seeded Jo-Wilfried Tsonga used 13 aces to overpower Jurgen Melzer 6-3, 6-2.

Djokovic initially struggled to return Soderling's hard serves. He managed a crucial break in the 10th game to take the first set.

Djokovic served for the match at 5-3 but he failed to close it out. He won the match in the 12th game when Soderling struggled to get his first serve into play.

"His game is based on powerful serves," Djokovic said. "I played him several times on different surfaces, so I was prepared for a difficult match."

Djokovic will face Thomas Berdych, who defeated Nicolas Mahut of France, 7-6 (6), 6-3.

Tsonga, reaching his first semifinal after a three-month break to undergo a knee operation, sailed through the match in just an hour.

"I was really concentrating and played better than the previous round. I'm happy to be in the semifinal," Tsonga said.

The Frenchman will take on countryman Gael Monfils on Saturday. Fourth-seeded Monfils advanced with a 7-6 (6), 6-4 win over Philipp Petzschner.

"It was a great match. Every match is tough, but Philipp played well," Monfils said. "He tried to keep the ball very low and he had a good serve."