Eugenie Bouchard insists there is no danger of her freezing on the big stage at Wimbledon.

At the age of 20, the Canadian already has semi-final runs at the Australian and French Opens behind her this season, and she heads into Wednesday's clash with Angelique Kerber attempting to reach the same stage at Wimbledon.

Kerber shocked Maria Sharapova in an epic fourth-round tussle on Tuesday, clinching a three-set victory on her seventh match point, as the race for the women's title was blown wide open.

At the bottom of the draw, Petra Kvitova knows she will face fellow Czech Lucie Safarova in the semi-finals on Thursday, but the top half remains at the quarter-final stage.

Germany's Sabine Lisicki, who was runner-up to Marion Bartoli 12 months ago, faces a tough but winnable Centre Court assignment against world number three Simona Halep on Centre Court at midday.

Bouchard and Kerber were set to go head to head on Court One at the same time.

And in her break-out season on tour, Bouchard said: " I've learned a lot. I think the main thing is the confidence I've added since the beginning of the year.

"I believe in myself. Every match I play, I believe I can win. I've proved to myself I can play on the big stage as well. I've played on centre courts of most of the slams, big moments, big matches. I'm proud of the way I can handle it out there."

Sharapova made a frustrated exit, 10 years after launching herself on the world stage as a 17-year-old with a stunning Wimbledon final triumph over Serena Williams.

Williams, meanwhile, departed the tournament on Tuesday after a viral illness left her unsteady and seemingly in a daze as she and sister Venus competed in the doubles. The 32-year-old served four consecutive double faults in the third game before the American sisters, both beaten in the third round of the singles, conceded their match to Kristina Barrois and Stefanie Voegele.

Kerber will be looking to carry on where she left off against Sharapova, after her sparkling 7-6 (7/4) 4-6 6-4 victory.

Bouchard beat Kerber in the French Open fourth round recently and that might be a relevant factor.

''But I'm feeling better now and I'm feeling better on grass,'' Kerber said after seeing off Sharapova. ''I've never played against her on this surface, so I will be focused just on myself. I'll just try to be aggressive, play my game, and not focus on her."

Halep was barely tested on Court Two by Zarina Diyas of Kazakhstan, dropping just three games, but Lisicki was given a thorough workout by Russian-born Kazakh Yaroslava Shvedova before poaching a 6-3 3-6 6-4 win.

Lisicki served 20 double faults and needed medical attention early in the final set, when she was facing break point against the serve but struggling with an arm problem.

There could be a doubt over her playing against Halep, as Lisicki said of the prospect: "I'll do everything I can.

"I'll go and see the doctor and physio and hope they'll be able to do some miracles."