Pushed to the absolute limit, Serena Williams once again found a way to win.
Down 3-0 and 5-4 in the third set, twice within two points of defeat, Williams dug deep and overcame Britain's Heather Watson 6-2, 4-6, 7-5 on Centre Court at Wimbledon on Friday to keep alive her bid for a fourth straight major title and the third leg of a calendar-year Grand Slam.
Next up for the five-time champion: a fourth-round matchup with sister Venus.
Top-ranked Serena looked on the ropes after losing six games in a row and going two breaks down in the third set. But, just as she has done so many times before, she refused to lose.
Williams ran off four games in a row as she battled back, and broke Watson in the 12th game to win on her third match point and extend her Grand Slam winning streak to 24 matches.
''I've had some tough losses, but that was probably my toughest match I've played (on Centre Court),'' Williams said. ''Heather playing in front of her home crowd ... I think she played unbelievable. She should have won the match at this point, she was up two breaks and she just really gave her all.''
The 59th-ranked Watson, lifted throughout the match by a raucous partisan crowd, played the match of her life but fell short of becoming the first British woman to beat a No. 1 since Sue Barker defeated Chris Evert in Boston in 1979.
''It was super, super close, and that's what hurts the most,'' Watson said.
Venus Williams, also a five-time champion, made it to the fourth round for the first time since 2011 by beating Aleksandra Krunic of Serbia 6-3, 6-2.
That sets up the 26th career meeting between the sisters - and the first at a Grand Slam since Serena won in the 2009 Wimbledon final. Overall, Serena leads 14-11.
''She's in better form than I am,'' Serena said of her older sister, ''so I think she has a little bit of an advantage going into that match. But at least one of us will be in the quarterfinals, so that'll be good.''
Serena, who lost in the third round here last year, has won the U.S. Open, Australian Open and the French Open since then. A Wimbledon win would give her another ''Serena Slam'' - four straight majors. Then, all that would be left would be the U.S. Open to complete the first calendar-year Slam since Steffi Graf in 1988.
Williams' match with Watson, played in windy conditions, had big swings in momentum.
From 4-3 down in the second set, Watson ran off six straight games to go up 3-0 in the third. Then Williams began her comeback by breaking Watson in a game that lasted 11 minutes. Watson was twice within one point of going up 4-0, but Williams eventually converted on the sixth break point.
Williams was erratic throughout the match and finished with 33 unforced errors, to go with 53 winners. Watson had only 11 unforced errors, with 20 winners.
While Williams overcame a huge challenge just to qualify for the second week, the top-ranked men's player - Novak Djokovic -hasn't faced much of a test so far in the defense of his Wimbledon title.
He's played three matches, won all in straight sets, and never dropped more than four games in any set.
The top-ranked Djokovic disposed of Bernard Tomic 6-3, 6-3, 6-3 on Centre Court to bolster his bid for a third Wimbledon title and ninth Grand Slam championship.
''I was hoping that I can play better and better as the tournament progresses and that's exactly what is happening right now,'' said Djokovic, who extended his career record against Tomic to 4-0. ''I think as I'm moving on through the tournament I feel more confident on the court.''
He'll next face big-serving Kevin Anderson, the 14th-seeded South African, who beat Leonardo Mayer of Argentina 6-4, 7-6 (6), 6-3.
Also advancing were French Open champion Stan Wawrinka, who swept Ferando Verdasco 6-4, 6-3, 6-4; Richard Gasquet, who dismantled No. 11 Grigor Dimitrov 6-3, 6-4, 6-4 on Centre Court; and Belgium's David Goffin, who downed Marcos Baghdatis in straight sets.
Nick Kyrgios -the 20-year-old Australian who stunned Rafael Nadal here last year - served 34 aces and hit flashy winners from all over the court to upset seventh-seeded Milos Raonic of Canada 5-7, 7-5, 7-6 (3), 6-3 to reach the round of 16 for the second year in a row.
In women's play, former champion Maria Sharapova beat 29th-seeded Irina-Camelia Begu of Romania 6-4, 6-3 and has yet to drop a set. The first woman to make it to the fourth round was American CoCo Vandeweghe, who beat former U.S. Open champion Samantha Stosur 6-2, 6-0. It's the first time the 47th-ranked Vandeweghe has reached the final 16 at a Grand Slam tournament.
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