Wimbledon 2017: Angelique Kerber fights back to beat Shelby Rogers

Top seed Angelique Kerber survived a scare against American world number 70 Shelby Rogers to reach the Wimbledon last 16.

Germany's Kerber, 29, lost a tight first set before fighting back to win 4-6 7-6 (7-2) 6-4 in a thrilling battle on court two.

She will face Spain's 14th seed Garbine Muguruza in the fourth round on Monday.

Kerber will lose her world number one ranking if she does not reach the final.

Muguruza, a Wimbledon finalist in 2015, powered to a straightforward 6-2 6-2 victory over Romania's Sorana Cirstea.

Second seed Simona Halep could take top spot from Kerber by reaching the semi-finals, while Karolina Pliskova - despite her second-round exit - still has a chance of taking it.

Two-time Grand Slam champion Kerber's form has dipped since winning the US Open last year. She has failed to win any tour titles since then and sits just 15th in the year-to-date rankings.

But the left hander, who was beaten by Serena Williams in last year's final, is known for her fighting qualities and needed to show all of them to beat Rogers in two hours and 17 minutes.

After Rogers won the opener with a single break of serve, Kerber cut down on the unforced errors as the American's aggressive style started to produce more mistakes than clean winners.

Kerber battled back from a break down in the second, winning three successive games before going on to dominate the tie-break.

The German took her seventh break point to nick a 13-minute opening game in the decider, then exchanged breaks again as the momentum swung between the players.

Kerber roared with relief as Rogers, bidding to reach the last 16 at Wimbledon for the first time, cracked a forehand long on the German's second match point.

"I think the key was at the end that I was fighting, and I was never giving up at the end, doesn't matter how the score was," Kerber said after the match.

• Federer and Djokovic win in straight sets

• Querrey beats Tsonga in five minutes

Muguruza in last 16 without dropping a set

Muguruza has not reached a final since winning Roland Garros last year

Muguruza, 23, has dropped down the rankings in recent months after struggling to sustain the form she showed to win last year's French Open.

But she has raced through the opening three rounds in SW19, winning her matches without dropping a set.

Cirstea, who progressed to the last 32 when opponent Bethanie Mattek-Sands suffered a serious knee injury, provided little resistance.

After the 27-year-old Romanian held in the opening games of each set, Muguruza rattled off five successive games in both to win in one hour and 10 minutes.

"I felt today I improved my game a bit compared to the previous matches," the Spaniard said. "I'm happy the way I'm playing out there.

"It's great to reach the second week. That's everybody's goal, to go through the first week, the first matches, then the exciting part comes now in a way."

• Live scores and schedule

• BBC coverage times and channels

• Take on the legends in our interactive game

Radwanska, Kuznetsova & Vandeweghe also through

Poland's Agnieszka Radwanska overcame a shaky first set to beat Swiss Timea Bacsinszky 3-6 6-4 6-1.

Radwanska, the world number 10, struggled to find her rhythm but took full advantage as Bacsinszky struggled to overcome a thigh injury.

Her backhand looked particularly strong as she reached the last 16 for the sixth consecutive year.

She will next face two-time Grand Slam champion Svetlana Kuznetsova, after the Russian's powerful 6-4 6-0 win over Slovenia's Polona Hercog.

The Russian converted four of six break points and showed a strong first serve as she beat Hercog in just over an hour.

American Coco Vandeweghe has yet to drop a set at Wimbledon after beating compatriot Alison Riske 6-2 6-4 on court three.

Her next opponent, Caroline Wozniacki, secured a remarkable 3-6 7-6 (7-3) 6-2 victory over Anett Kontaveit.

Wozniacki was a set down and Kontaveit served for the match in the second, but the Dane managed to turn around her performance and throw her opponent's big-serving game off balance.