Seven-time champion Serena Williams makes her singles comeback at Wimbledon on Tuesday, as Rafael Nadal continues his pursuit of a calendar Grand Slam.
American Williams, 40, plays France's Harmony Tan on Centre Court, 12 months on from tearing her hamstring in her first-round match at SW19.
Women's world number one Iga Swiatek opens play on the main show court against Croat Jana Fett from 13:30 BST.
Men's second seed Nadal, a two-time winner, then meets Francisco Cerundolo.
A 23-time Grand Slam singles champion, Williams made her long-awaited return to action in the doubles at Eastbourne last week alongside Ons Jabeur, after ending speculation over her future in the sport by accepting a Wimbledon wildcard.
She is one short of Australian player Margaret Court's record of 24 Grand Slam singles wins.
"I didn't retire. I just needed to heal physically, mentally. I had no plans, to be honest. I just didn't know when I would come back," Williams said.
"I didn't know how I would come back. Obviously Wimbledon is such a great place to be, and it just kind of worked out."
French Open champion Swiatek, 21, enters Wimbledon on an impressive 35-match winning run which has taken her level with Venus Williams for the longest WTA victory streak this century.
The Pole's match against world number 252 Fett is followed by 22-time major winner Nadal's return for the first time since 2019, after the Spanish world number four was able to recover from treatment on a chronic foot injury in time for the Championships.
"I can walk normal almost every single day. That for me is the main issue. When I wake up, I don't have this pain that I was having for the last year and a half, so I'm quite happy about that," said Nadal.
On Court One, Italy's 2021 men's runner-up Matteo Berrettini faces Chilean Cristian Garin, before 2019 women's champion Simona Halep meets Karolina Muchova.
Men's Greek fourth seed Stefanos Tsitsipas closes play against Swiss player Alexander Ritschard.
What about the Brits?
British men's number two Dan Evans gets his tournament under way in the final match of the day on court two, where he meets Australian Jason Kubler.
Meanwhile, fellow Briton Paul Jubb, 22, faces a tough task against Australia's Nick Kyrgios on court three.
Over on court 12, Eastbourne semi-finalist Jack Draper, 20, takes on Belgian Zizou Bergs, after Ryan Peniston contests his postponed day-one match against Swiss Henri Laaksonen.
Katie Swan also saw her match cancelled on Monday following rain delays and returns to play Ukraine's Marta Kostyuk on court 18, where Katie Boulter and Harriet Dart are later in action.
Boulter is up against France's Clara Burel, before Dart and Spanish player Rebeka Masarova compete for a place in the second round.
Jay Clarke will return to complete his suspended match against American Chris Harrison, with the Briton currently trailing 7-6 (7-3) 6-1 5-5, and Heather Watson's opener against German Tamara Korpatsch must also be completed after Watson had tied the match 7-6 (9-7) 5-7.