NEW YORK (AFP) - A tested Serena Williams battled through her own mistakes and the tension of her quest for tennis history Friday to reach the US Open fourth round.
The 33-year-old American fought back to defeat 101st-ranked compatriot Bethanie Mattek-Sands 3-6, 7-5, 6-0 at Arthur Ashe Stadium and needs only four more triumphs to complete the first calendar Slam since Steffi Graf in 1988.
Williams struggled with her serve early and made half her 28 unforced errors in the first set, but found her form late in the second set and dominated from there.
"I'm not trying to live on the edge," Williams said.
"I don't think I came out too slow. I think Bethanie came out really well. I had to adapt to her game and I finally got some rhythm going toward the end of the second set." Williams, holder of all four major titles, also seeks her 22nd career Slam singles crown to match Graf's Open Era record and move two shy of Australian Margaret Court's all-time mark.
Williams, who could reach her first Grand Slam final without facing a top-10 foe, next plays US 19th seed Madison Keys, who beat Polish 15th seed Agnieszka Radwanska 6-3, 6-2.
"I only have one match I'm looking forward to and that's the next one," Williams said. "This journey has been great. Every night I come out it feels better and better." On the men's side, top-ranked Novak Djokovic moved a step closer to his 10th career Slam crown and third of the year by defeating Italy's Andreas Seppi 6-3, 7-5, 7-5, while Rafael Nadal faced 32nd-seeded Italian Fabio Fognini in a later match.
Mattek-Sands, her blonde hair tinted witrh tangerine dye, took charge early, leading 3-0 and breaking back to 4-2, then holding twice to claim a first set where Williams was 1-7 on break chances.
It was not unfamiliar territory as Williams went to three sets for the 10th time in 24 Grand Slam matches this year and stayed perfect.
Older sister Venus Williams, 35, eased Serena's path to the final by ousting the top-rated rival on that side of the draw, defeating 12th-seeded Swiss teen Belinda Bencic 6-3, 6-4.
Bencic, 18, inflicted the most recent defeat upon Serena last month in a Toronto semi-final, but fell to 0-4 against Venus.
Venus, 35, fired 31 winners against 15 unforced errors while Bencic had 12 of each.
"I just wanted to be aggressive," Venus said. "Keeping the errors down really helped me close out the match." Venus, seeded 23rd, reached a fourth-round match against 152nd-ranked Estonian teen qualifier Anett Kontaveit and could face Serena after that.
"I hope we both get to the quarter-finals," Venus said.
Djokovic took his 31st win in a row over Italian foes, 11 of them against Seppi, since losing to Filippo Volandri in his ATP debut at Umag in 2004.
"It was a tough three sets," Djokovic said. "Just hanging in there. Be patient for your opportunities. You try to cash in when they come." Next up is Spanish 23rd seed Roberto Bautista Agut, who advanced when 14th-seeded Belgian David Goffin retired while leading 6-2, 7-5, 3-6, 1-3.
A Grand Slam record 13 men have retired from matches at this tournament, with two women quitting during matches as well, many from heat-related cramping issues.
Spanish eighth seed Nadal, a 14-time Grand Slam champion on a quarter-final collision course with Djokovic, hopes to beat Fognini and next face Spanish 18th seed Feliciano Lopez, who eliminated Canadian 10th seed Milos Raonic 6-2, 7-6 (7/4), 6-3.
Croatian ninth seed Marin Cilic barely escaped making the earliest exit of any defending champion since 1999 before outlasting 56th-ranked Kazak Mikhail Kukushkin 6-7 (5/7), 7-6 (7/1), 6-3, 6-7 (3/7), 6-1.
"It wasn't easy but I stayed together and got it done," Cilic said.
Not since Andre Agassi lost to Arnaud Clement 16 years ago in the second round had a men's champion been ousted before the fourth round.
Cilic next meets French 27th seed Jeremy Chardy, who ousted Spanish seventh seed David Ferrer 7-6 (8/6) 4-6, 6-3, 6-1.
France's Benoit Paire reached his first Grand Slam fourth round with a 7-6 (7/3), 6-1, 6-1 victory over Spain's Tommy Robredo. He next faces countryman Jo-Wilfried Tsonga, who beat Ukraine's Sergiy Stakhovsky 6-3, 7-5, 6-2.
Russian 13th seed Ekaterina Makarova fought off cramping to oust Ukraine 17th seed Elina Svitolina 6-3, 7-5 and is now the top-ranked rival in the Williams half of the draw.
Makarova, playing with a taped upper right leg, began cramping while serving at match point. Told she could not see a trainer until a changeover, she fought on and advanced on a forehand winner.
"I was scared," Makarova said. "It's the first time I was cramping. She told me she can't treat me until the changeover. I kept playing and kept trying."