Six-times champion Serena Williams has stormed into the Australian Open semi-finals, extending her run of dominance over Maria Sharapova to 18 matches.

Williams wasn’t always at her best on Tuesday and spoke with the doctor and trainer during a lopsided second set.

But the world No.1 did more than enough to silence Sharapova 6-4 6-1 in one hour and 32 minutes on Rod Laver Arena.

Williams will step up her bid for a 22nd grand slam title on Thursday, when she faces Agnieszka Radwanska for a place in Saturday’s decider.

Earlier on Tuesday, Radwanska became the first woman through to the Open semi-finals when she defeated Carla Suarez Navarro 6-1 6-3.