London - Serena Williams's chances of winning an eighth Wimbledon and 24th Grand Slam title were boosted on Friday when Madison Keys became the seventh top 10 seed to be eliminated.
Tenth seed Keys, who had made at least the quarter-finals of her last three majors, lost in the third round 7-5, 5-7, 6-4 to Russian qualifier Evgeniya Rodina, ranked 120th in the world.
She joins defending champion Garbine Muguruza, world No 2 Caroline Wozniacki, two-time champion Petra Kvitova and US Open winner Sloane Stephens in falling in the first week.
Serena, seeded 25 this year after taking time away from the tour to give birth to her daughter, faces Kristina Mladenovic of France for a place in the last 16 later Friday.
The 36-year-old American now cannot meet a top 32 player until the semi-finals after the scattering of the seeds this week.
Keys lost nine games on the trot from 5-2 up in the first set to 0-4 down in the second.
She rallied to level the third-round match before Rodina sealed a maiden place in the last 16 of a major.
Keys fired 15 aces in the match but also committed 48 unforced errors.
"I have played the qualies and three matches this week which were all three sets," said 29-year-old Rodina, one of six mothers in the draw at the start of the tournament.
"She hits the ball so hard. I am a little surprised that I won, I was a little bit lucky today."
Later Friday, eight-time champion Roger Federer takes on German comeback specialist Jan-Lennard Struff.
The world No 64 has had to fight back from two sets to love down in his first two matches to beat Leonardo Mayer and 39-year-old Ivo Karlovic.
Defending champion and top seed Federer, by contrast, has made the third round without breaking sweat.
The 36-year-old Swiss has won 26 consecutive sets at the All England Club.
Federer beat Struff in the second round of the Australian Open in January in straight sets.
German fourth seed Alexander Zverev made the third round, seeing off Taylor Fritz of the United States 6-4, 5-7, 6-7 (0/7), 6-1, 6-2 and faces Latvian qualifier Ernests Gulbis for a spot in the last 16.
Zverev had trailed two sets to one when his tie with Fritz was halted due to darkness on Thursday.
But the 21-year-old raced away with the last two sets in Friday's bright sunshine.
"Stopping last night was not a nice feeling to go to bed with," said Zverev.
"But I knew if I took my chances today, I could do well."
"I am having a good season - made the quarters at the French Open - it's all coming together."
Russia's Ekaterina Makarova defied second round victim Wozniacki's churlish prediction that she wouldn't progress further in the tournament by reaching the last 16.
Makarova, who made the quarter-finals four years ago, beat a weary-looking Lucie Safarova of the Czech Republic 4-6, 6-1, 6-4.
She next faces Italy's Camila Giorgi who saved a match point to beat Katerina Siniakova of the Czech Republic 3-6, 7-6 (8/6), 6-2.
Giorgi last made the fourth round six years ago.
Five-time champion Venus Williams, 38, and making her 21st Wimbledon appearance, faces fellow big server Kiki Bertens of the Netherlands.
Williams has dropped the opening set in both her matches so far and needed to save match points to beat Bertens in Miami this year.
READ: Anderson marches into Wimbledon 4th round
South Africa's Kevin Anderson, seeded eight, swept past Germany's Philipp Kohlschreiber 6-3, 7-5, 7-5 on the back of 22 aces and 42 winners.
Anderson has reached the last 16 for the fourth time and goes on to face either Sam Querrey of the United States or France's Gael Monfils.
Wimbledon results on Friday, the fifth day of the 2018 championships (x denotes seeded player):
Alexander Zverev (GER x4) bt Taylor Fritz (USA) 6-4, 5-7, 6-7 (0/7), 6-1, 6-2
Gael Monfils (FRA) bt Sam Querrey (USA x11) 5-7, 6-4, 6-4, 6-2
Kevin Anderson (RSA x8) bt Philipp Kohlschreiber (GER x25) 6-3, 7-5, 7-5
Donna Vekic (CRO) bt Yanina Wickmayer (BEL) 7-6 (7/2), 6-1
Evgeniya Rodina (RUS) bt Madison Keys (USA x10) 7-5, 5-7, 6-4
Camila Giorgi (ITA) bt Katerina Siniakov (CZE) 3-6, 7-6 (8/6), 6-2
Ekaterina Makarova (RUS) bt Lucie Safarova (CZE) 4-6, 6-4, 6-1