World No. 1 and defending champion Iga Swiatek pulled out of the Miami Open on Wednesday due to a rib injury.

Swiatek had received a first-round bye in the hard-court tournament. The 21-year-old native of Poland last played on Friday when she lost in the semifinals to eventual tournament champion Elena Rybakina of Kazakhstan in the BNP Paribas Open at Indian Wells, Calif.

Swiatek said in a statement Wednesday that she has been dealing with the injury since winning the Qatar TotalEnergies Open last month.

"You know that in and after Doha, I was struggling with a strong infection," Swiatek said. "I was allowed to play, but a strong episode of tough cough led to a rib injury. We were trying to handle it and continue to play as long as it was safe for me. We were analyzing the data in the last days and my doctor prepared my diagnosis.

"Unfortunately, I'm still feeling a lot of discomfort and pain and I can't compete."

Swiatek also said she will sit out Poland's Billie Jean King Cup qualifier against Kazakhstan on April 14-15.

"I will keep you updated about where I play next, because it depends on my process of recovering and the recommendation of my medical team," Swiatek said. "I have the best team behind me, we only need some time to deal with the injury. It's a truly difficult call to not play in Miami and BJKC, but health is the most important.

"I'm grateful this is the first health issue in a long time and I was able to compete in perfect shape for so long, but that's sports, it happens sometimes, without our control. Time to accept it and get well as soon as possible."

Lucky loser Julia Grabher, who fell in qualifying, will replace Swiatek and face Claire Liu on Thursday in the second round of the Miami Open.