SERENA WILLIAMS, chasing a calendar Grand Slam, advanced to a dramatic U.S. Open quarterfinal showdown with sister Venus while a concussion forced Canada’s Eugenie Bouchard out of the tournament.

    World No. 1 Serena served well in moving within three match victories of a 2015 sweep of major titles by defeating U.S. 19th seed Madison Keys 6-3, 6-3 Sunday.

    Looking ahead, No. 1 Serena described No. 23 Venus this way: “It’s like playing a mirror.”

    Serena took only 68 minutes to dismiss Keys, a 20-year-old American with formidable serves and forehands, who simply was outplayed.

    Already a winner of the past four major tournaments, including last year’s U.S. Open, Serena is trying to become the first tennis player to win all four in the same season since Steffi Graf in 1988.

    Asked why it’s been so long since anyone else pulled off a true Grand Slam, Serena paused for effect, smiled and answered: “I don’t know why it took me so long.”

    Standing in the way at the moment is Venus. This will be the 27th all-Williams match over their long and successful careers, and Serena leads 15-11, including 8-5 at majors. Each has beaten the other twice at the U.S. Open, with Venus winning the 2001 final and Serena the 2002 final.

    “It’s about, of course, forgetting that she’s playing Venus,” said Serena’s coach, Patrick Mouratoglou.

    Venus, at 35 the oldest woman in the tournament, was on court even less time than her sibling Sunday, overwhelming 19-year-old qualifier Anett Kontaveit of Estonia 6-2, 6-1 in 50 minutes.

    Venus, of course, knows full well the challenge that awaits today.

    “What else can you do, except try to win the point and hope she doesn’t hit an ace?” said Venus, who lost in the third round or earlier at each of the past four U.S. Opens.

    The sisters’ mother, Oracene Price, said she wouldn’t attend the quarterfinal. As for whether Venus will be in a tough spot — hoping to win, yet also well aware of what her sibling is pursuing — Price said: “I know it’s going to be hard, because I know (Venus) wants (Serena) to get it.”

    Another women’s fourth-round match scheduled for Sunday was scratched when 25th-seeded Eugenie Bouchard withdrew with a concussion, two days after slipping and falling in the locker room. That allowed Roberta Vinci of Italy to advance to the quarterfinals.

    (SD-Agencies)