Wimbledon 2017, Day 6: Top seed Angelique Kerber lives to fight another day, Garbine Muguruza powers into fourth round

London: Top seed Angelique Kerber lived dangerously for more than two hours before finally subduing the tenacious challenge of American outsider Shelby Rogers 4-6 7-6(2) 6-4 to reach the Wimbledon fourth round on Saturday.

The German, who was runner-up to Serena Williams last year, has struggled for form in recent months and at times was blasted off court by Rogers` heavy hitting from the baseline.

However, the world number one kept faith with her error-filled game plan to seal victory when Rogers, ranked 70th in the world, belted a service return long.

She will face 2016 French Open champion Garbine Muguruza on Monday for a place in the quarter-finals.

Former runner-up Garbine Muguruza continued her untroubled progress with a 6-2 6-2 thrashing of Romania`s Sorana Cirstea to reach the fourth round.

Cirstea, who reached the third round after American opponent Bethanie Mattek-Sands suffered a horrible knee injury on Thursday, matched Muguruza for power but made too many errors to pose a serious threat to the 14th seed.

The Romanian held on to her opening service game with an ace but Muguruza was quickly into her groove and reeled off the next five games before Cirstea managed to stem the tide briefly.

The same happened in the second set. Cirstea again held in the opening game with a backhand winner, before Muguruza changed gear and went on a five-game streak.

Muguruza, 23, showed there was more to her game than power with some silky dropshots as she powered on to victory in a little over an hour on Court Two.

She will face top seed Angelique Kerber in the next round.

Another former grand slam champion, Svetlana Kuznetsova, eased into the second week with a 6-4 6-0 defeat of Polona Hercog of Slovenia.

Coco Vandeweghe also continued her seamless progress at Wimbledon as she booked her spot in the fourth round with a 6-2 6-4 win over fellow American Alison Riske.

The 24th seed, who is coached by former men`s winner Pat Cash, has yet to drop a set in her three opening matches and is looking a good bet to defy the odds as the women`s draw becomes increasingly hard to predict.

While her form has swung between the extremes of a semi-final run to the Australian Open in January and a first round exit at the French Open in May, she has some pedigree on grass, having reached the quarter-finals at Wimbledon in 2015.

She has hired Cash hoping he can give her an extra edge, 30 years after the head-band wearing Australian lifted the trophy at the All England Club.

She broke twice to race through the opening set against Riske and twice more at the start of the second to take a 4-0 lead.

The wheels threatened to come off at that stage as her compatriot fought back to level at 4-4.

Vandeweghe, however, steadied her nerves to break again and set up three match points with an ace before checking out with a service winner.