Serena Williams steamrolled Samantha Stosur 6-1, 6-1 on Saturday to reach the final of the WTA tour\'s green clay Charleston tournament. Williams needed just 59 minutes to subdue the second-seeded Australian, who beat the American in the US Open final last September but has now lost to her twice in two events. In Sunday\'s final, the fifth-seeded American will face ninth-seeded Czech Lucie Safarova, who notched her own lopsided semi-final win 6-0, 6-0 over Slovenia\'s Polona Hercog. Williams improved to 6-3 overall against Stosur, including a straight-sets victory in Miami 11 days ago in which Williams fired 20 aces. Williams had a relatively sedate seven aces on Saturday. She saved both break points she faced and broke Stosur five times as the Australian failed in a bid to become just the eighth player to beat both Williams sisters in the same tournament. Stosur defeated Venus Williams in the quarter-finals to spoil the chance of an all-Williams semi. Safarova, owner of four WTA Tour titles, will try to add a first victory in one of the WTA\'s premier level events. Her emphatic victory over Hercog, in 64 minutes, ended a dream run for the Slovenian that included a first career win over a top-10 player with her upset of third-seeded Marion Bartoli in the third round, and a quarter-final triumph over former Charleston champion Nadia Petrova.