NEW HAVEN, Conn. (AP) — Caroline Wozniacki advanced to the second round of the New Haven Open when Peng Shuai was forced to retire while up a set on the four-time tournament champion Monday night.
Peng was leading 6-2, 1-3 when the chair umpire announced the Chinese player could not continue due to illness. Tournament officials later said she was suffering from dizziness.
Peng, who has a history of heart problems, spent an extended time with a trainer after Wozniacki asked for a coach while leading 3-0 in the second set.
WTA officials said Peng was examined by medical personnel after the match, but had no further details.
The 27-year-old pursued a pro tennis career despite having heart surgery when she was 12 years old. Her ordeal was the subject of an Adidas advertising campaign "Impossible is Nothing."
"She felt a bit dizzy and obviously from the flight and everything, she played the doubles finals in Cincinnati last night," Wozniacki said. "Flying in here and having to play the same day is obviously tough."
Peng broke Wozniacki twice in the first set. But Wozniacki seemed to turn things around in the second game of the second set, which included seven deuces and Peng holding an advantage five times.
Wozniacki, seeded fourth in the tournament, improved to 21-1 in her six years in New Haven. Her only loss here came in last year's semifinals when she retired due to a knee injury.
"It's a great tournament for me, what else can I say," she said.
Earlier, American Sloane Stephens beat Anna Schmiedlova of Slovakia 6-4, 6-4, The sixth-seeded Stephens, the top-ranked American in the draw, broke Schmiedlova in the third game of the match, while reeling off 13 straight points. The two traded breaks in the second set until Stephens held serve to go up 4-2.
She will play German Julia Goerges in the second round. Goerges advanced with a 6-2, 4-6, 7-5 win over Bojana Jovanovski of Serbia.
Stephens, who beat Serena Williams to reach the semifinals of the Australian Open in January and made the quarterfinals of Wimbledon in July, came into the match ranked 17th in the world.