NEW YORK — Back in January, when Aryna Sabalenka was winning a second consecutive Australian Open title, Jessica Pegula was bowing out in the second round with a straight-set loss against someone ranked 51st.

It wasn’t the first setback for Pegula, of course. There have been many of those through the years, from assorted injuries to difficult-to-digest defeats. Look at her now, though: On Saturday, the No. 6-seeded Pegula will face No. 2 Sabalenka for the championship at the U.S. Open.