Serena Williams boosted her chances of winning an eighth Wimbledon and 24th Grand Slam by making the fourth round at the All England Club on Friday as big sister Venus fell victim to the curse of the seeds. Serena, seeded a modest 25 this year, enjoyed a 7-5, 7-6 (7/2) win over France's Kristina Mladenovic to set up a last-16 duel with Russian qualifier -- and fellow mother -- Evgeniya Rodina. Only two of the top 10 seeds remain in the women's draw -- number one Simona Halep, who plays her third round match on Saturday, and seventh seed Karolina Pliskova who came back from 1-4 down in the second set to defeat Mihaela Buzarnescu 3-6, 7-6 (7/3), 6-1. While the women's draw was being blown wide open, it was business as usual for defending men's champion Roger Federer who enjoyed a 6-3, 7-5, 6-2 win over Germany's Jan-Lennard Struff.
Serena said she was delighted to be into the second week at Wimbledon.
"I have worked really hard and it's been a long arduous road," said Serena, playing in just her second Slam since the birth of her daughter Olympia last September.
"A lot of top players have lost. Technically I am not a top player although I have the wins of one."
Venus, 38 and the runner-up last year, was worn down by Dutch 20th seed Bertens who next faces Pliskova.
"It means a lot. It was such a tough match and such a big fight so I'm really happy that I won this one," Bertens said.
Also exiting was 10th seed Madison Keys, who had made at least the quarter-finals of her last three majors.
The American lost 7-5, 5-7, 6-4 to Rodina, ranked 120th in the world.
"I have played the quallies and three matches this week which were all three sets," said 29-year-old Rodina.
"She hits the ball so hard. I am a little surprised that I won, I was a little bit lucky."
Federer took his consecutive sets won at Wimbledon to 29 in what was his 200th career grass court match.
The eight-time champion will face French 22nd seed Adrian Mannarino on Monday for a place in the quarter-finals.
"I was happy to stay clam and finish off the job. I thought I did very well today," said the 36-year-old 20-time Slam winner.
"I created more chances in the second set and was always able to stay pretty clean on my own service games."
Stefanos Tsitsipas became the first Greek man in the Open era to make the last 16 of a Slam as the 31st seed beat Italian qualifier Thomas Fabbiano 6-2, 6-1, 6-4.
The 19-year-old will faces US ninth seed John Isner for a place in the quarter-finals.
- Zverev, Anderson through -
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 who said he had vomited on Friday due to a stomach bug and came close to quitting.
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.
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 France's Gael Monfils.