WASHINGTON — Top women's seed Simona Halep retired from her quarter-final match at the Citi Open on Friday because of the heat, allowing Russia's Ekaterina Makarova to advance to the semifinals.

Halep, ranked second on the WTA Tour, retired trailing 1-0 in the third set after she and the seventh-seeded Makarova split the first two. Fourth-seeded German Julia Goerges beat sixth-seeded Monica Niculescu 6-3, 6-4, to advance.

Later in the day, Germany's Andrea Petkovic defeated Toronto teenager Bianca Andreescu 6-7 (3), 6-1, 6-2.

On the men's side, eighth-seeded American Jack Sock defeated Thornhill, Ont., product and third-seeded Milos Raonic 7-5, 6-4 to reach the semifinals.