(Reuters) - Venus Williams fended off three match points before outlasting Dutch 29th seed Kiki Bertens 5-7 6-3 7-5 in a three-hour marathon to reach the fourth round of the Miami Open on Sunday. Ukrainian fourth seeded Elina Svitolina, Latvia's Jelena Ostapenko and British defending champion Johanna Konta also won their third round encounters. Svitolina outlasted Daria Gavrilova of Australia 4-6 6-0 6-1 and the sixth seeded Ostapenko turned back Brazil's Beatriz Haddad Maia 6-2 7-6(2).