Wozniacki reaches Miami quarterfinals when Muguruza retires

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.