NEW YORK — For eight intense, entertaining games, Sloane Stephens stayed right with Serena Williams.
For a 40-minute stretch in the fourth round of the U.S. Open, the top two American women put on quite a show. Both hit serves topping 115 mph. Both whipped groundstrokes to the corners. Both covered a lot of ground, extending points with leg-churning defense. Both showed the occasional sign of nerves, reflecting what a big deal this was, in part because the 15th-seeded Stephens already was one of only three players to beat No. 1 Williams this season.