This market refers to the tennis match between Marta Kostyuk and Sloane Stephens in the US Open WTA, originally scheduled for September 2, 2026 at 11:00AM ET. This market will resolve to 'Marta Kostyuk' if Marta Kostyuk advances against Sloane Stephens. This market will resolve to 'Sloane Stephens' if Sloane Stephens advances against Marta Kostyuk. If the match is canceled (not played at all), ends in a tie, or a winner has not been determined by September 16, 2026, 11:59 PM ET (14 days after the scheduled start), this market will resolve to 50-50. If the match begins but is not completed, and one player advances due to the opponent's retirement, default, or disqualification, this market will resolve to the player who advances. If the match ends in a walkover (player withdraws before the start and the other advances automatically), this market will resolve to 50-50. The primary resolution source will be official information from the WTA Tour. A consensus of credible reporting may also be used.