Andujar beat Lukas Rosol 6-4, 6-3. He had four breaks and won just one fewer (35-36) point off Rosol's serve than Rosol managed.
Andujar will next go against Benoit Paire, the only unseeded player to make the semifinals. Paire rallied for a 0-6, 6-2, 7-5 win over third-seeded Jarkko Nieminen. Nieminen won 61 percent of the points in the first set but Paire won 59 percent the rest of the way.
Also Friday, fourth-seeded David Nalbandian topped Joao Souza 6-3, 6-2. Nalbandian was good on just 45 percent of his first serves but lost just one service game.
Nalbandian is 2-0 versus Seppi, but they haven't played each other since 2006. Andujar and Paire are paired against each other for the first time.