seeded American Mardy Fish shook off a sluggish start to beat Gilles Muller 7-6 (7/1), 6-1 Thursday and reach the quarterfinals of the $619,500 ATP Los Angeles hardcourt tournament. Fish, ranked ninth in the world, was playing his first match since winning his sixth career title with a victory over John Isner in the Atlanta final Sunday. The first set went with serve from there, and Fish built momentum heading into the tiebreaker when he closed out the 12th game with two straight aces. Once he had sped through the tiebreaker, Muller offered little resistance. “He's a guy that plays very well ahead, or equal,” Fish said. In Friday's quarterfinals Fish will face eighth-seeded Igor Kunitsyn of Russia. Kunitsyn defeated tenacious American Ryan Sweeting 7-6 (7/4), 7-6 (8/6). Fourth-seeded Brazilian Thomaz Bellucci roared into the quarterfinals downing Colombia's Alejandro Falla 6-0, 6-1 in 51 minutes. Like Fish, Bellucci enjoyed a first-round bye. But the 34th-ranked Brazilian wasted no time to close out the match. Bellucci next faces American Alex Bogomolov, who upset seventh-seeded Bulgarian Grigor Dimitrov of Bulgaria 6-4, 6-3. Cilic in semis In Croatia, fourth-seeded Croat Marin Cilic defeated Italy's Andreas Seppi Friday to reach the semifinals of the Croatia Open. Cilic cruised to victory, beating the seventh-seeded Seppi 6-1, 6-3 in just 72 minutes. Cilic will next face another Italian, sixth-seeded Fabio Fognini, who rallied from one set down to defeat last year's finalist Potito Starace 3-6, 6-3, 6-1. Second-seeded Alexandr Dolgopolov recorded another straight-set victory, defeating Spaniard Albert Ramos 6-3, 7-5.