Iga Swiatek of Poland returns a ball to Jessica Pegula in the quartefinals in Arthur Ashe Stadium at the 2024 US Open Tennis Championships in at the USTA Billie Jean King National Tennis Center, Sept. 4, in New York City. UPI-Yonhap

World No. 1 Iga Swiatek pulled out of the Korea Open tennis tournament Friday, becoming the latest big name to withdraw from the lone WTA competition in South Korea.

Organizers of the Korea Open said Swiatek, a five-time Grand Slam singles champion, withdrew from the competition due to fatigue.

They said the Polish player told them she was not back to 100 percent following the U.S. Open last week and was forced to alter her schedule. Swiatek promised to visit Seoul for next year's tournament, the organizers added.

Swiatek is one of five current or former top-10 players to have withdrawn from the Korea Open.

Jessica Pegula, the defending champion with a Korean-born mother, will miss her title defense here due to a rib injury. Pegula, world No. 3, knocked off Swiatek in the quarterfinals of the U.S. Open before losing to Aryna Sabalenka in the final.

World No. 4 Elena Rybakina, the 2022 Wimbledon champion, has hit the sidelines with a back injury, while eighth-ranked Emma Navarro, the U.S. Open semifinalist, has changed her schedule. Karolina Pliskova, former world No. 1 and 2014 Korea Open champion, is dealing with a foot injury.

With these withdrawals, the 2017 U.S. Open champion Sloane Stephens and the 2021 U.S. Open winner Emma Raducanu have moved into the main draw.

Raducanu was a fan favorite at the 2022 Korea Open, when she reached the semifinals -- her first trip to the last four at a tournament that year.

The Korea Open starts Saturday with qualifying matches at Olympic Park Tennis Center in Seoul, and the main draw matches will begin Monday. The finals for both the singles and doubles will be Sept. 22.

The Korea Open has been elevated from WTA 250, the lowest level of tour events, to WTA 500, meaning the champion will earn 500 world ranking points. The purse has been raised from about $260,000 to $1 million. (Yonhap)