Iga Swiatek was stunned by Emma Navarro in the third round of the China Open on Wednesday.
The battle for the WTA's year-end world No. 1 ranking is set for another dramatic finish, with Iga Swiatek closing the gap on Aryna Sabalenka ahead of the WTA Finals.
World No. 1 and defending US Open champion Aryna Sabalenka says rivals Iga Swiatek and Coco Gauff present "the biggest challenge" to her on a physical level.
Amanda Anisimova stunned world number two Iga Swiatek in straight sets in the US Open quarterfinals at Flushing Meadows on Wednesday.
Second seed Iga Swiatek's sublime summer continued with a record-breaking opening-round victory at the US Open on Tuesday.
Third seed Iga Swiatek sealed her place in the Cincinnati Open final with an impressive win against Elena Rybakina on Sunday.