Two of tennis' top women's singles competitors are matched up today as Sloane Stephens faces the  top-ranked Serena Williams in the fourth round. Serena's looking to add to her US Open resume, which includes four singles titles and two doubles titles, including a singles win at least year's tournament. As Serena looks to defend her championship, she'll have to defeat the red-hot Sloane Stephens. In the second set, Williams is currently up 6-4, 3-1. The winner will advance to the quarterfinals, which begin on Tuesday.

Serena's wearing her Nike Lunar Mirabella 3 PE, which unfortunately is not available to the public. To shop Nike's current women's tennis line, click here. Be sure to stick with Sneaker Report for ongoing US Open coverage as the action heats up.

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