Marta Kostyuk vs Madison Keys: Set 1 Winner

This market focuses on predicting which player will win the first set of a professional tennis match between Marta Kostyuk and Madison Keys at the 2026 WTA Toronto Round of 32. The outcome depends solely on the result of the first set, regardless of the final match result. Various scenarios such as match cancellations, postponements, or retirements are accounted for in how the market will be settled.