LONDON -- Just after the top handful of elite players, women's tennis recently has been a volatile cocktail of nerves and self-doubt.
To keep you busy while we anticipate Super Monday, when the Williams sisters collide at Wimbledon for the sixth time, here are the Power Rankings of the 16 women remaining. Strangely enough, a 35-year-old, five-time champion heads the list:
1. No. 16 Venus Williams: Venus has won each of her six sets and dropped only 15 games en route to a tantalizing matchup with younger sister Serena. Truth be told, Venus is playing better. But with a calendar-year Grand Slam on the line, Serena will a difficult out.
2. No. 4 Maria Sharapova: It's been 11 years since she broke through here as a 17-year-old, but Sharapova is 0-for-10 since. She's sailed through the draw, dropping only 15 games in six sets.
3. No. 15 Timea Bacsinszky: A year ago, the 26-year-old Swiss player had to qualify her way into the main draw. Now, she's into the second week after surprising former Wimbledon finalist Sabine Lisicki 6-3, 6-2. Up next: unseeded Monica Niculescu.
4. No. 21 Madison Keys: Through three matches, the 20-year-old American is leading the tournament with 42 aces. The Australian Open semifinalist has a very reasonable path to the quarterfinals, where she will face Jelena Jankovic. This is Keys' best Wimbledon so far.
5. Belinda Bencic: The 18-year-old Swiss player looks like a future Grand Slam winner. She trailed Bethanie Mattek-Sands 5-1 in the third round and rallied to win in straight sets. Bencic is the tournament leader in break points converted (18).
6. No. 5 Caroline Wozniacki: The great Dane has won all six sets, although there have been a few tight ones. Not Saturday, though, when Wozniacki hammered No. 31 seed Camila Giorgi 6-2, 6-2. Her fourth-round opponent: Garbine Muguruza.
7. No. 23 Victoria Azarenka: After a down year, Azarenka is slowly gathering strength as the season progresses. She's lost only 17 games, and a win in the fourth round against Belinda Bencic would land Azarenka in a quarterfinal match against one of the Williams sisters.
8. No. 28 Jelena Jankovic: No. 2 seed Petra Kvitova had dropped only three games through her first two matches, but the defending champion was stunned by Jankovic in three sets. It was the fifth time Jankovic advanced to the fourth round -- but she's never gone further.
9. No. 13 Agnieszka Radwanska: On paper, the Pole has had one of the tournament's best runs, dropping only a dozen games in three matches. Despite a mediocre year, Radwanska is dangerous here as a former finalist here (2012) and semifinalist (2013).
10. No. 1 Serena Williams: She dropped that second set against Heather Watson but prevailed in a memorable third-round match. Serena has been dodgy at times, but she's won her last 24 Grand Slam singles matches.
11. No. 6 Lucie Safarova: The French Open finalist has lost the first set in two of her three matches but managed to advance. She produced an impressive third-round win against American Sloan Stephens.
12. No. 20 Garbine Muguruza: The 21-year-old from Barcelona, Spain, has been extended to three sets the past two times out, but she's a fighter. Her third-round victim was No. 8 seed Angelique Kerber, a semifinalist here three years ago and a quarterfinalist in 2014.
13. Coco Vandeweghe: The 23-year-old American blew 2011 U.S. Open champion Samantha Stosur off the court, winning the last 12 games of their third-round match. Vandeweghe has 28 aces, tied for second (with Jankovic) in the tournament.
14. Monica Niculescu: The unseeded Romanian knocked off Kristyna Pliskova in the third round. The 27-year-old came into the tournament with three lifetime Grand Slam wins. She now she has three in the same week.
15. Zarina Diyas: The 21-year-old from Kazakhstan raced up the WTA rankings ladder last year, from No. 163 to No. 34. She's dropped only one set so far and scored a nice win over No. 14 Andrea Petkovic in the third round.