Seven-time champion Serena Williams makes her singles return at Wimbledon on Tuesday as Rafael Nadal continues his pursuit of a calendar Grand Slam.
A year after tearing her hamstring in her first-round match at SW19, American Williams is playing France's Tan on Centre Court.
The women's world number one is playing on the main show court against a Croat.
Nadal, a two-time winner, faces Francisco Cerundolo.
After ending speculation over her future in the sport by accepting a Wimbledon wild card, Serena Williams made her long-awaited return to action in the doubles at Eastbourne last week.
Margaret Court had 24 Grand Slam singles wins.
I did not stop working." "I did not stop working." "I did not stop working." "I did not stop working." "I did not stop working." I needed to heal my body and mind. I had no idea what I was going to do. Williams didn't know when he would return.
I didn't know how I would return. It just kind of worked out that Wimbledon is a great place to be.
Swiatek enters Wimbledon on an impressive 35- match winning run which has taken her level with Venus Williams for the longest win streak this century.
The Pole's match against Fett is followed by Nadal's return after the Spaniard recovered from a foot injury in time for the Championships.
I can walk most of the time. It's the main issue for me. "When I wake up, I don't have the pain that I was having for the last year and a half, so I'm quite happy about that."
On Court One, Italy's 2021 men's runner-up Matteo Berrettini will face his opponent.
The fourth seed from Greece is playing against the Swiss player.
British men's number two Dan Evans gets his tournament under way in the final match of the day on court two, where he is scheduled to face Australia's top ranked male player.
Paul Jubb is up against Australia's Nick Kyrgios on court 3.
After Ryan Peniston contests his postponed day-one match against Swiss Henri Laaksonen, Jack Draper is on court 12.
After her match was canceled on Monday due to rain, she returned to play the Ukrainian on court 18.
Boulter is up against France's Clara Burel before the other two players compete for a spot in the second round.
Jay Clarke will return to complete his suspended match against American Chris Harrison, with the Britons currently trailing 6-1 5-5, and Heather Watson's opener against German Tamara Korpatsch must also be completed after she tied the match at 7.