Eugenie Bouchard has pulled out of the Wuhan Open, citing medical problems from the concussion she suffered at the U.S. Open.
Bouchard said she was suffering extreme headaches on Saturady.
Her withdrawal came several hours before her first scheduled match, against Belinda Bencic of Switzerland.
Bouchard is currently classified as 36th in the world by the WTA.
The 21-year-old suffered the concussion after falling in a locker room on Sept. 4.
In other matches at the tournament Italy's Roberta Vinci fought back to beat qualifier Danka Kovinic of Montenegro 5-7, 6-1, 6-3 in the opening round of the Wuhan Open on Monday, her first match since falling to countrywoman Flavia Pannetta in the U.S. Open final.
The 15th-seeded Vinci was broken three times in the opening set, but picked up her game to win the next two sets and the match in just under two hours.
At the U.S. Open earlier this month, Vinci stopped Serena Williams' bid for a calendar-year Grand Slam by upsetting the American in the semifinals.
Meanwhile ninth-seeded Ana Ivanovic of Serbia defeated Alexandra Dulgheru of Romania 6-1, 6-3, and Sloane Stephens of the United States beat countrywoman Alison Riske 7-6 (4), 6-3.
With a file from The Canadian Press
