NEW YORK — Now comes a challenge for Venus Williams and Serena Williams at the U.S. Open: a match against each other.
Except unlike so many of their all-in-the-family face-offs at Grand Slam tournaments, including at Wimbledon in July, this Williams vs. Williams showdown will not decide the championship. Instead, this one will come in the quarterfinals.
Both advanced through the fourth round quite easily Monday. The No. 7-seeded Venus dismissed No. 9 Agnieszka Radwanska of Poland 6-1, 6-3, before No. 4 Serena dispatched wild-card entrant Severine Bremond of France 6-2, 6-2 at night.
"Even the semis would have been better than the quarterfinals, but at least one of us will make it to the semis," Serena said. "I've got probably the toughest match of the tournament coming up next, so I've got to be ready."
The sisters' matchup Wednesday will be a tiebreaker of sorts.
They've played 16 times as professionals, with each winning eight. That includes 10 meetings at major tournaments, with each winning five. The most recent was when Venus beat Serena for the title at the All England Club, the seventh all-Williams Grand Slam final.
"I would love to have a winning record," Venus said.
But because of the luck of the pre-tournament draw, they were placed in the same portion of the bracket — much to the disappointment of them, U.S. Open organizers and TV types.
"The best part is that we're still here," Venus said, "going stronger than ever, in my opinion."
That is certainly true: Venus has lost a total of 15 games through four matches at Flushing Meadows, while Serena has lost 14.
Of the eight women left in the tournament, only two have won a Grand Slam title: Serena leads all active players with eight, and Venus is right behind with seven.
They won every U.S. Open women's singles championship from 1999 to 2002, meeting in the finals the last two years in that span. Since then, though, Serena hasn't made it past the quarterfinals here, and Venus has only reached one semifinal.
Also advancing to the women's quarterfinals with victories Monday were No. 6 Dinara Safina, who defeated Anna-Lena Groenefeld 7-5, 6-0, and No. 16 Flavia Pennetta, who beat No. 32 Amelie Mauresmo 6-3, 6-0.
In men's action, No. 1 Rafael Nadal faced a tough challenge from 55th-ranked Sam Querrey, a 20-year-old Californian who never before had been to the fourth round at a major tournament.
Querrey hung in during extended baseline rallies, and even briefly led in the third set, before losing 6-2, 5-7, 7-6 (2), 6-3.
"Very tough," Nadal said. "Sam is a big player, a big server. He has a great future."
Nadal owns four titles from the French Open and one from Wimbledon, but he's never been as far as the U.S. Open semifinals. He'll try to take care of that gap on his resume when he meets another unseeded American, Mardy Fish, in the quarterfinals.
Fish beat a seeded player for the third consecutive match, serve-and-volleying his way past No. 32 Gael Monfils in straight sets Monday.
No. 17 Juan Martin del Potro of Argentina ended the run of Kei Nishikori, the first Japanese man to reach the U.S. Open's fourth round in the 40-year Open era. Del Potro won the contest between teenagers 6-3, 6-4, 6-3 for his 23rd consecutive victory.
Del Potro will face No. 6 Andy Murray, who beat 10th-seeded Stanislas Wawrinka 6-1, 6-3, 6-3.