Williams took the first set before the second set went into a tie-breaker, but the former world number one finished with a flourish taking the final set 6-3 to win the match.

Meanwhile, the second-seeded Sofia Kenin was stunned with a straight-sets 6-3, 6-3 defeat to the 16th seeded Belgian, Elise Mertens.

Victoria Azarenka in her turn advanced to the last eight with a 7-5, 6-1, 6-4 win over the Czech Republic's Karolina Muchova.

Williams will now square off against Tsvetana Pironkova on Wednesday in the quarter-finals, with Naomi Osaka set to face Shelby Rogers.

In the men’s section, the quarter-finals start on Tuesday with a match between Borna Coric and Alexander Zverev.

@SamLudidi OFM Sport