Quarterfinal spots on the line. #USTennis stars @serenawilliams, @johnrisner, and @sloanestephens will battle today in the R16 at the #USOpen. Tune-in to @espn all day and @espn 2 at night to catch the 🇺🇸 #tennis #serenawilliams #williams #serena #johnisner #isner #sloane #sloanestephens #bigjohn