Serena Williams moved up one spot Monday from No. 2, swapping places with Angelique Kerber.
The return to No. 1, which gives the 35-year-old American her 317th week there, comes less than a week after Williams let the world know via Snapchat that she is pregnant.
The baby is due in the fall, and spokeswoman Kelly Bush Novak said Williams will take off the rest of this season and intends to return to the tour next year.
Williams confirmed that timetable on Instagram on Monday, when she posted a photo of herself and a note addressed to “My Dearest Baby.”
“You gave me the strength I didn’t know I had. You taught me the true meaning of serenity and peace. I can’t wait to meet you. I can’t wait for you to join the player’s box next year. But most importantly, I am so happy to share being number one in the world with you . . . once again today,” the post reads.
Williams closed it with: “From the world’s oldest number one to the world’s youngest number one. -Your Mommy”