The new tennis rankings are honoring her top ranking from last fall.
Peterson defeated Kazakh Jelena Rybakina in Sunday's final in Nanchang by clear 6–2, 6–0. It was the 24-year-old's first title in singles, she has one in double since before.
"It feels fantastic to take the first WTA title," Peterson told SVT Sport.
For her, the title came as no surprise.
- I've played many tough games this year. It has helped me, and I have been in many pressure situations. I've taken a lot of that with me, ”she says.
She now travels in China to Canton where she is faced with the toughest conceivable resistance in the first round - the first-seeded Jelina Svitolina.
The Ukrainian, US Open semi-finalist a few weeks ago, remains in third place on the world rankings after Australian Ashleigh Barty and Czech Karolina Pliskova.