NEW YORK, USA (AFP) — Serena Williams advanced to a US Open quarter-final showdown against her sister Venus and moved three wins shy of a calendar Grand Slam by defeating Madison Keys 6-3, 6-3 yesterday.

World number one Serena, who holds all four major titles, dispatched the US 19th seed to reach a last-eight date with Venus, who earlier eliminated Estonian teen qualifier Anett Kontaveit 6-2, 6-1.

Serena, two years younger than Venus at 33, holds a 15-11 edge in the sibling rivalry, most recently winning in fourth round at Wimbledon in July.

But they have split four US Open meetings, including the 2001 final won by Venus and 2002 final won by Serena.

Venus Williams advanced by defeating 152nd-ranked Estonian teen qualifier Anett Kontaveit 6-2, 6-1 yesterday.

Canada’s Eugenie Bouchard, who suffered a head injury after slipping in the US Open locker room late Friday, was set to face Italy’s Roberta Vinci in a late last-16 match.

The winner will meet either Russian 13th seed Ekaterina Makarova or France’s Kristina Mladenovic in the quarter-finals.

Venus, who lost the 1997 US Open final to Martina Hingis when Kontaveit was 21 months old, broke in the fourth game and and in the eighth, Kontaveit hitting a forehand long to drop the set after 24 minutes.

Kontaveit, who lost in the first round at the past two Wimbledons in her only prior Grand Slam appearances, swatted a forehand beyond the baseline to give Venus a 2-0 lead in the second set and sent a backhand long to surrender a break for a 4-0 deficit. Williams held twice more, denying the European’s lone break point in the final game to win in 50 minutes.

Kontaveit, 19, was thwarted in her bid to match the best US Open qualifier showing, American Barbara Gerken’s quarter-final run in 1981.

Even with the loss, Kontaveit will nearly double her career prize money with $213,575 for her US Open run.