The U.S. Open's first round begins on Sunday with defending women's champion Aryna Sabalenka looking to recapture top form, while former men's champion Daniil Medvedev faces a familiar foe whom he has failed to beat in previous meetings. TOP WOMEN'S MATCH: ARYNA SABALENKA V REBEKA MASAROVA Sabalenka finally won the U.S. Open last year, after two semi-final exits then loss in the 2023 final. But defending the crown has proven tough for most, with the women's singles tournament producing 10