Serena's fourth US Open semis in five years

US fourth seed Serena Williams advanced to the US Open semi-finals for the fourth time in five years on Wednesday by defeating Serbian 12th seed Ana Ivanovic 6-1, 6-3

Three-time champion Williams, a 14-time Grand Slam winner who lost to Samantha Stosur in last year's final, will next play today against Italian 10th seed Sara Errani for a berth in Saturday's championship match.

Serena Williams celebrates her victory over Ana Ivanovic. Pic/AFP

"It's going to be a good matchup. She is such a fighter. She's so strong and quick," Williams said. "I'm just so happy to be in the semis. It's so cool."

Williams has only dropped 16 games through five matches while blasting a tournament-best 41 aces, including 12 against outmatched Ivanovic, a former World No 1 who won a Grand Slam title at the 2008 French Open.