Serena Williams is through to the quarter-finals of the US Open following a straight sets victory over Madison Keys on Sunday
The 33-year-old is bidding to become only the fourth female player in history to win four Grand Slam titles in the same year
She will come up against her sister Venus in the last eight following her straight sets victory over qualifier Anett Kontaveit
The next installment of Serena Williams' quest to complete the calendar Grand Slam could be the most dramatic or awkward yet – a quarter-final against her sister Venus.
The world No 1 one appeared to have cured herself of recent wobbles by beating outstanding young American Madison Keys 6-3, 6-3 on Sunday night, a far easier progression than against lesser opponents last week.
She now faces Venus, at 35 in her 35th Grand Slam last eight after she dismissed qualifier Anett Kontaveit 6-2, 6-1.
Serena was transformed from the nervous figure seen in the first two rounds, her game much improved against Keys, often touted as her eventual successor at the top of American women's tennis and possibly the whole game.
Keys gave her plenty of pace to work with, and Williams's whole game was much tighter, making only six unforced errors with no double faults. She faced no break points and is now three matches away from becoming only the fourth woman in history to win all four Majors in a year.
