Muller will face 2005 champion Ivan Ljubicic, who beat Dutch qualifier Igor Sijsling 6-4, 6-3.

Ljubicic fired 13 aces, including one on match point.

The fourth-seeded Croatian took the first set on a double-fault from Sijsling, who was playing his first quarterfinal on the main tour. Ljubicic then broke serve to lead 4-2 in the next set.

The 49th-ranked Muller was at his shot-making best in the first set, hitting 19 winners to only five for Gasquet.

Muller cracked three aces in a row to win the opening set. In the second set, he broke at 1-1 and saved five break points to clinch victory when Gasquet sent a backhand return long.

In Bucharest, Romania, top-seeded Juan Ignacio Chela advanced to the semifinals of the Nastase Tiriac Trophy on Friday by beating seventh-seeded Andreas Seppi of Italy 7-5, 6-3.

Seppi led 5-3 in the first set after breaking Chela in the seventh game, but the Argentine broke back twice take the lead.

Chela will face fourth-seeded Pablo Andujar of Spain, who defeated qualifier Alessandro Giannessi of Italy 6-3, 6-4. Chela beat Andujar in last year's Bucharest final.

Second-seeded Florian Mayer of Germany also reached the semifinals and will play against Filippo Volandri of Italy.

Mayer defeated Albert Ramos of Spain, 6-1, 6-2, while Volandri beat Brazilian Joao Souza 6-2, 6-0.

In Seoul, South Korea, Maria-Jose Martinez Sanchez reached the Korea Open semifinals Friday by beating third-seeded Julia Goerges of Germany 7-6 (6), 6-1.

The sixth-seeded Spaniard will next meet Klara Zakopalova of the Czech Republic on Saturday in the semifinals at the Olympic Park. Zakopalova defeated Vania King of the United States 6-2, 4-6, 6-1.

Also, fifth-seeded Polona Hercog of Slovenia beat fourth-seeded Dominika Cibulova of Slovakia 6-3, 6-1 and Galina Voskoboeva of Kazakhstan defeated Vera Dushevina of Russia 6-2, 6-3.