In 2009, Serena and Venus Williams played against each other for the fourth time in a span of eight Wimbledon finals.
They haven't met in an all-Williams match at the All England Club since.
With one victory apiece Friday, they will set up the latest installment of their historic sibling rivalry at the grass-court tournament, only this time it would be in the fourth round.
First things first.
The No. 1-seeded Serena takes a 23-match Grand Slam winning streak into the third round against 59th-ranked Heather Watson of Britain on Centre Court.
Little doubt who most of the spectators will be pulling for.
"I've been used to playing against a lot of local people. Doesn't matter what country it's in. Hopefully, that will help me a little bit," Serena said. "The home court will probably help her a little bit."
The 16th-seeded Venus, meanwhile, will face 82nd-ranked Aleksandra Krunic of Serbia on Court 2.
Each Williams sister has won five Wimbledon titles.
That includes when Serena beat Venus in the 2002, 2003 and 2009 finals, part of her total of 20 major singles trophies. And when Venus beat Serena in the 2008 final for the most recent of her seven Grand Slam championships.
"I give her as good a chance as anybody to win the title," said Venus' coach, David Witt. "You've still got to go out there and do it, regardless of who's the favorite, who's the underdog. It comes down to, when you go out there, who's serving better ... (and) who's being aggressive."
Krunic has never faced Venus, nor has she ever played in the main draw at Wimbledon before.
Watson, meanwhile, has never faced Serena, nor has she ever been past the third round at her country's home tournament.
The one other time Watson made it this far at Wimbledon, in 2012, she managed to win only two games in a loss to eventual runner-up Agnieszka Radwanska.
"I wasn't sure how to deal with it. I remember overplaying totally and thinking she was going to be this amazing player that, you know, I'm going to have no chance against. I tried to hit winners on the first ball. That was no good," Watson recalled. "This time around, this isn't my first, second or third Wimbledon. I've been here a few times now. I've gotten a feel for playing the top players. At the end of the day everybody's human. Everybody's going to make mistakes. Everybody is going to have good days and bad days."
Here's what else is happening Friday at Wimbledon:
AUSSIE, AUSSIE, AUSSIE!
A couple of young Australians aim for upsets in the men's draw: 27th-seeded Bernard Tomic takes on No. 1 Novak Djokovic, the defending champion, on Centre Court, while No. 26 Nick Kyrgios faces No. 7 Milos Raonic, a semifinalist in 2014, on Court 2. Tomic, 22, was a quarterfinalist at Wimbledon back in 2011. Kyrgios, 20, knocked off two-time champion Rafael Nadal in the fourth round a year ago.
CILIC VS. ISNER
Reigning U.S. Open champion Marin Cilic of Croatia, who's seeded No. 9, plays No. 17 John Isner of the U.S. on Court 1. "The thing that (Cilic) does the best, in my opinion: He's always calm and composed on the court. He's never getting angry at himself out there," Isner said. "He just stays the path, and it's paid very big dividends for him in his career, especially last year at the U.S. Open."
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