There were contrasting fortunes for Angelique Kerber and Karolina Pliskova at Wimbledon, while there was concern for Bethanie Mattek-Sands on Thursday.

This year, Kerber has so far failed to match her stunning exploits of 2016 where she won two grand slams and reached the final of Wimbledon, while Pliskova has three titles to her name and leads the WTA's Road to Singapore.

But as Kerber marched on at SW19, Pliskova - one of the pre-tournament favourites - waved goodbye for another 12 months. Here we take a look at the main talking points of the women's draw on day four.

KERBER ON THE UP, PERIL FOR PLISKOVA 

Kerber twice found herself a break down in the first set against Kirsten Flipkens and lost her nerve when serving for the match at 5-4 in the second, but the German eventually prevailed 7-5 7-5 to set up a third-round tie with Shelby Rogers.

But it was a disappointing day for the much-fancied Pliskova. The Czech was downed 3-6 7-5 6-2 by world number 87 Magdalena Rybarikova, who now holds an impressive 15-1 record on grass this year.

HERCOG ENDS SEVEN-YEAR ITCH

Over seven years ago, Polona Hercog played a third-round match at the French Open. It has been a long wait for the Slovenian to reach such a stage at a grand slam once more.

But the 26-year-old, ranked a lowly 265, defeated Varvara Lepchenko 6-7 (2-7) 6-2 6-2 to reach the third round here.

Hercog's reward? A date with Svetlana Kuznetsova (7), who was a comfortable 6-0 7-5 victor over Ekaterina Makarova.

HORROR FALL FOR MATTEK-SANDS 

There were troubling scenes on Court 17 as Mattek-Sands suffered an "acute knee injury" as a result of a horrific fall in her encounter against Sorana Cirstea. 

The American's right leg buckled as she approached the net during the deciding set and she could be heard screaming "please, help me".

She was treated on court and taken away in an ambulance after being comforted by doubles partner Lucie Safarova, with whom she was aiming to complete a non-calendar Grand Slam.

RADWANSKA SURVIVES, RISKE REWARDED

Agnieszka Radwanska (9) almost became a big second-round casualty on Thursday as the unfancied Christina McHale earned two match points in a second-set tie-break. Normal service resumed in the decider, though, as the Pole won through 5-7 7-6 (9-7) 6-3.

Kristina Mladenovic (12) was not so lucky, though. The Frenchwoman was felled 2-6 6-4 6-4 by Alison Riske, who goes on to face American compatriot Coco Vangeweghe.

Caroline Wozniacki (5), Garbine Muguruza (14) and Timea Bacsinszky (19) each secured safe progression with straight-sets wins.