Pliskova, Williams in Wimbledon 4th round

Pritha Sarkar
Serena Williams' is the only former champion to make the Wimbledon round of 16

Serena Williams remains on track for an eighth Wimbledon crown, but sister Venus and fellow American Madison Key joined the unprecedented exodus of the women's seeds on day five.

Karolina Pliskova is now the only top-10 women's seed through to the second week, with eight others eliminated, and world No.1 Simona Halep looking to join her when she plays Taiwan's Su-Wei Hsieh on Saturday.

The Czech avoided the cull by beating Romania's Mihaela Buzarnescu 3-6 7-6(3) 6-1 on Friday afternoon.

Once the seventh seed survived a second set tiebreak, she raced through the decider to make it through to the second week for the first time in seven attempts.

Seven-times champion Serena William also cruised into the last 16 after recovering from a sluggish start to beat France's Kristina Mladenovic 7-5 7-6 (1).

The American, seeded 25, looked sluggish initially and trailed 5-3 but the 36-year-old flicked the switch and reeled off six games in a row as Mladenovic wilted in the heat.

Williams has now won 17 consecutive matches at Wimbledon including the 2015 and 2016 titles.

She missed last year's tournament because she was pregnant with daughter Alexis Olympia.

But Williams' five-time Wimbledon champion sister Venus won't be joining her the fourth round.

The ninth seed American lost to 20th seed Kiki Bertens of the Netherlands 6-2 6-7 (5) 8-6 in the third round.

In each of her first two matches this week, the older Williams sister dropped the opening set before eventually winning in three.

She couldn't quite do the same this time.

Bertens is due to face Pliksova in the round of 16

Earlier on Friday, American 10th seed Madison Keys also fell to Russia's Evgeniya Rodina 7-5 5-7 6-4.

The 23-year-old, coached by Australian Dave Taylor, looked like salvaging a place in the last 16 when she clawed her way back from a set and 4-0 down to take the match into a decider on a hot and humid Court Three.

But world No.120 Rodina, who needed treatment early in the decider, refused to crack and broke the Keys serve at 4-4.

Rodina got to match point with a stunning forehand pass played almost on her knees. Keys then netted a forehand, her 48th unforced error of the match, to hand the Russian victory.

Rodina now faces Serena Williams in her next match.

Since tennis turned professional in 1968, it is the worst showing at Wimbledon by the women's seeds.