LONDON, England – No.4 seed Angelique Kerber booked her place in the last 16 of Wimbledon with a straight set victory over Carina WItthoeft on Saturday.

While her title rivals labored, Kerber has quietly gone about her business in the opening week, continuing her unfettered progress with a 7-6(11), 6-1 win over fellow German Witthoeft.

An evenly contested first set looked to be going Kerber’s way when she broke in the 11th game. However, Witthoeft hit straight back, capitalizing on a series on uncharacteristic errors from the No.4 seed. This fighting spirit was evident in the tie-break, too, a series of winners helping her fend off four set points before a relieved Kerber converted at the fifth time of asking.

The second set was a more stop-start affair, Kerber taking a couple of rain delays in her stride to secure a fourth-round meeting with Misaki Doi.

A warm embrace between compatriots Kerber and Witthoeft as the No.4 seed advances to the fourth round#Wimbledon https://t.co/ECgQhRbd1w

— Wimbledon (@Wimbledon) 2 July 2016

Kerber is through to the second week at the All England Club for just the third time in her career, and despite finding herself in a wide-open section of the draw will not be looking beyond Doi. At this January’s Australian Open, the German came from match point down to defeat Doi en route to the title.

“I am expecting a really close match. She is a lefty, as well. We never played on grass before. I think this is also a little bit different than to Australia,” Kerber said about her rematch with Doi. “But I know that she is a tough opponent. I was match point down in Australia.

“But I will try not to think about who I’m playing. I will go out there trying to play my game like always, and let’s see.”

There were also hard-fought wins for Sloane Stephens and Timea Bacsinszky in a couple of the rain-affected second-round matches. Resuming midway through the final set, No.18 seed Stephens held her nerve to see off Mandy Minella, 3-6, 7-6(6), 8-6.

Meanwhile, Bacsinszky, the No.11 seed, came out all guns blazing against Monica Niculescu, reeling off six straight games to close out a 4-6, 6-2, 6-1 victory.