New York, Sep 7 (IANS/EFE): Serena Williams defeated 19th-seeded Madison Keys 6-3, 6-3 and moved into the quarterfinals of the US Open where she will play her older sister Venus.

The world No.1 female tennis icon took just 68 minutes to crush the 20-year-old Keys, while Venus, 35, triumphed 6-2, 6-1 in her earlier match -- albeit in even less time, 52 minutes -- against Estonia's 19-year-old Anett Kontaveit.

The Estonian served well, as did Serena, but wracked up 19 unforced errors to six for her rival, including six double-faults, with most of at unlucky points in the match.

Serena has won the past four major tennis tournaments, including the US Open last year and is trying to become the first player to win all four Grand Slam titles in one season since Steffi Graf accomplished the feat in 1988.

The duel between the Williams sisters will be their 27th meeting on the court, with Serena holding the lead in past encounters 15-11, including her victory over Venus at Wimbledon.