KEY BISCAYNE, Fla. (AP) Caroline Wozniacki has reached the quarterfinals of the Miami Open, advancing Monday when Garbine Muguruza retired after one set with a heat-related illness.
Wozniacki, the sixth seed, took that set over the 12th-seeded Muguruza 7-6.
Muguruza was tended to by doctors following that tiebreaker, which wrapped up a 70-minute set, and decided she could not continue on a 77-degree, humid afternoon.
Wozniacki still has not dropped a set in the tournament, and will face fourth-seeded Dominika Cibulkova or Lucie Safarova in the quarterfinals.
Earlier Monday, Karolina Pliskova also reached the quarterfinals, beating Czech Fed Cup teammate - and occasional doubles partner - Barbora Strycova 6-1, 6-4. Pliskova needed only 21 minutes to take the first set, winning 11 consecutive points in one stretch and 16 of 17 on her serve.