Key volleys seal match-tiebreak for Siegemund and Zvonareva in Cancun
No.6 seeds Laura Siegemund and Vera Zvonareva started their play at the GNP Seguros WTA Finals Cancun with a 6-3, 6-7(6), [10-5] victory over 2021 champions Barbora Krejcikova and Katerina Siniakova.