Serena Williams is through to the Australian Open semi-finals after a brilliant and gutsy 6-3, 6-3 victory over the number two seed Simona Halep in Melbourne on Tuesday. Despite 33 unforced errors Williams claimed the last five games to beat Halep at the quarter-final stage and set up a showdown with Naomi Osaka for a place in the final. Williams is seeking a record-tying 24th major singles championship. The 39-year-old was outstanding in the first set but had a bit of a wobble early in the second to trail 3-1. Williams managed to turn the set back in her favour and broke into a huge smile when her forehand winner sealed the victory. Seeking an eighth Australian Open title, Williams will play Osaka on Thursday for a place in Saturday's final.