MASON, Ohio - Top-ranked Novak Djokovic advanced to the Western & Southern Open semifinals by dispatching fifth-seeded Stan Wawrinka 6-4, 6-1 in their quarterfinal match on Friday.

Djokovic, who lost to the Wawrinka in the French Open final, will play either sixth-seeded Tomas Berdych or qualifier Alexandr Dolgopolov in a Saturday semifinal.

Djokovic, the reigning Australian Open and Wimbledon champion, has never won a W&S championship. He is hoping to become the first man to win all nine ATP Masters 1000 championships in his career.

Wawrinka, who needed three tiebreakers and 2 hours, 37 minutes to get past 7-foot Ivo Karlovic on Thursday, committed 27 unforced errors to eight for Djokovic.

At 4-4 in the first set, Djokovic broke Wawrinka and went on to win the next five games, taking command of the match before closing it out in just 63 minutes.

"I think maybe I'm a little bit empty mentally to stay at my top," Wawrinka said. "I'm generally happy with my tournament. I know where I am. There is a lot of positives to take from this week — winning two tough matches without playing my best tennis, fighting, staying there.

"I think my level is there. I know and I can see where I am. I'm happy with the way and what I did this week. I'm excited for US Open."

Djokovic improved to 18-4 in his career against Wawrinka.