Right after relinquishing the No. 1 ranking two months ago, Iga Swiatek couldn’t help but worry about trying to regain it. “It’s hard not to think about stuff like that,” she explained.

And then Swiatek realized it was better to set that sort of thing aside and, instead, simply focus on playing her best tennis—and her best is better than anyone else’s at the moment. Swiatek earned her first WTA Finals title and clinched the year-end No. 1 ranking by overwhelming Jessica Pegula 6-1, 6-0 on Monday in the latest in a series of dominant performances.