US Open ’19: No. 1 Osaka defends; Serena Williams eyes 24th

              FILE - In this Sept. 8, 2018, file photo, Naomi Osaka, of Japan, kisses the trophy after defeating Naomi Osaka, of Japan, in the women's final of the U.S. Open tennis tournament in New York. Osaka is ranked No. 1 heading into the U.S. Open, where she will attempt to defend a Grand Slam title for the first time. (AP Photo/Julio Cortez, File)

Women to watch at the U.S. Open, where play begins Monday: