London: Serena Williams takes the starring role on 'People's Sunday' at Wimbledon when she tackles Germany's Annika Beck looking for a 300th Grand Slam win and a spot in the last 16.
Defending champion Williams is chasing a seventh All England Club title and an Open era record-equalling 22nd Grand Slam trophy.
She has never met 22-year-old Beck, the world number 43, and will be heavy favourite with the German only having won one match on four previous visits before this year.
"I do believe that every match I do plan on getting better," said the 34-year-old American.
"I hope to play more matches to get better. I'm ready for it. I'm ready for any challenge."
A 300th win at the majors will take her to within six of Martina Navratilova's all-time record.
For only the fourth time in history, and first since 2004, play is taking place on the middle Sunday as organisers try to clear the backlog caused by days of heavy rain.
The All England Club put 22,000 tickets on general sale for Sunday which took just 27 minutes to sell out. Around 111,000 people tried to purchase them.
American 27th seed Coco Vandeweghe gets action under way on Centre Court against veteran Italian sixth seed Roberta Vinci who shocked Serena in the US Open semi-finals last year.
The 24-year-old Vandeweghe made the Wimbledon quarter-finals in 2015.
The programme on the main court concludes with German teenager Alexander Zverev facing 2010 runner-up Tomas Berdych.
Tenth seed Berdych is bidding to record his first win against a seed at Wimbledon since 2013.
The German, who is through to the third round at Wimbledon for the first time, is hoping to record his first win against a seed at a Grand Slam.
The men's draw is still reeling from Saturday's shock exit of defending champion Novak Djokovic in the third round.
Andy Murray will now be the joint-favourite with Roger Federer to succeed Djokovic.
Murray doesn't play Sunday but he will take a keen interest in the tie between Australian 15th seed Nick Kyrgios and Feliciano Lopez, the Spanish 22nd seed.
Murray will face the winner of that third round clash which was one set apiece when play was halted for bad light on Saturday.
Kyrgios was at the centre of a new row on Sunday when he was heard labelling one of his own support team as "retarded".
The incident, picked up by microphones on Court One, occurred during the second set of his third round match.
US 18th seed John Isner is two sets to one ahead of French 12th seed Jo-Wilfried Tsonga in their clash.
On Court 12, French 32nd seed Lucas Pouille leads former US Open champion Juan Martin del Potro 6-7 (7/4), 7-6 (8/6), 7-5.
That match will resume with both men having bickered and argued for large parts of Saturday's action.
On Court One, Russian 13th seed Svetlana Kuznetsova, a three-time quarter-finalist, tackles American 18th seed Sloane Stephens.