Acapulco, Mexico: Fourth-seeded Juan Ignacio Chela advanced to the semifinals of the Abierto Mexicano on Thursday, beating sixth-seeded Nicolas Massu 6-3, 6-7 (6), 7-5."It's always tough to play against Massu," said Chela after battling for hours against the Chilean. "But, he made some mistakes, and I took advantage of them."Chela will face Argentine countryman Agustin Calleri, a 6-3, 6-4 winner over Jose Acasuso, in the semifinals.Chela, who was the runner-up from last year's tournament, has lost his past four meetings against Calleri. "Every match is different. Agustin is a very good player. I have to play great tomorrow to beat him. Right now I'm thinking more about havig a good sleep," Chela said.Moya advancesIn a late game, Spaniard Carlos Moya beat his countryman Nicolas Almagro 7-6 (3), 6-3 and will face the winner between Juan Carlos Ferrero and Gaston Gaudio.In the other quarterfinals on Thursday night, top-seeded Juan Carlos Ferrero faced fifth-seeded Gaston Gaudio, and third-seeded Nicolas Almagro was set to play eighth-seeded Carlos Moya.In women's play, fifth-seeded Flavia Penetta - the 2005 winner and 2006 runner-up - beat Alize Cortne 7-5, 6-4 to set up a semifinal match against the winner of the late match between second-seeded Tathiana Garbin and Sara Errani.Emilie Loit also advanced, beating sixth-seeded Gisela Dulko 5-7, 6-4, 6-1. Loit will face the winner of the late match between Julia Schruff and Melissa Torres.