Serena Williams has set up a Wimbledon last-16 showdown with sister Venus after surviving a major scare as Maria Sharapova also eased into the second week.
Top seed Serena, bidding for a sixth Wimbledon title and already halfway to a calendar grand slam after wrapping up the Australian and French Opens, defeated unseeded Briton Heather Watson 6-2 4-6 7-5 in a Centre Court thriller.
Watson, the world number 59, served for the match at 5-4 in the final set after being a double break up but her nerve failed her against the 33-year-old American she idolised as a child.
“I’ve had some tough losses but that was probably my toughest match playing Heather in front of her home crowd,” said Serena, who is chasing a 21st Grand Slam title.
“She played unbelievable and really I think she should have won the match.”
Venus, also a five-time champion and playing in her 18th Wimbledon, reached the fourth round with a 6-3 6-2 win over Serbia’s Aleksandra Krunic.
Serena will face her 35-year-old sister on Monday for the first time in a grand slam since beating her in the 2009 Wimbledon final.
“We have a lot of respect for each other,” said Venus. “There’s no easy points when we face each other.”
Watson admitted her big chance had passed her by.
“I was two points away from winning the match, so I am pretty disappointed,” said the 23-year-old.
Sharapova, the 2004 champion, made the last 16 with a 6-4 6-3 win over Romania’s Irina-Camelia Begu and goes on to tackle unseeded Zarina Diyas of Kazakhstan for a spot in the quarter-finals.
“What everyone at this stage of the tournament expects is to go further and expect more, better things from yourself. As the matches get tougher, you have to raise your level,” said five-time grand slam winner Sharapova.
America’s Coco Vandeweghe reached the last 16 at a Slam for the first time with a 6-2 6-0 win over 2011 US Open champion Sam Stosur of Australia.
Stosur has yet to get beyond the third round at Wimbledon in 13 years of trying.
Vandeweghe will next face Czech sixth seed Lucie Safarova, who beat Sloane Stephens of the United States 3-6 6-3 6-1.
Teenager Belinda Bencic became the first Swiss woman into the fourth round since Patty Schnyder in 2007 when she defeated American qualifier Bethanie Mattek-Sands 7-5 7-5 after trailing 5-1 in the first set.
Former world number one and two-time semi-finalist Victoria Azarenka made the last 16 with a 6-4 6-4 win over France’s Kristina Mladenovic and next faces Bencic.