Image: Serena Williams of the US plays a shot against her compatriot Madison Keys during their US Open women's singles match in New York on September 6, 2015 (AFP Photo/Jewel Samad)
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 Sunday.
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, owns 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.
