NEW YORK • Eugenie Bouchard's entry into the second week of the US Open was supposed to have coincided with the return of her new coaching consultant, Jimmy Connors. He had planned to rejoin her if she reached the fourth round.

Instead, she will not play at all.

Tournament director David Brewer said on Sunday the 25th-seeded Bouchard, a 21-year-old Canadian, had pulled out, citing a concussion in a locker-room accident.

She suffered the injury late on Friday night, after her mixed doubles victory with Nick Kyrgios in the first round.

With the locker room empty and dark as Bouchard entered for an ice bath, she slipped on the recently-cleaned floor and fell, hitting her elbow and head.

Still struggling with typical concussion symptoms - a severe headache, sensitivity to light and noise - Bouchard withdrew on Saturday from her women's doubles and mixed-doubles matches on the advice of tournament doctors.

On Sunday, she withdrew from the singles, allowing Italian Roberta Vinci to advanced to a quarter-final against Kristina Mladenovic.

Bouchard had been in the midst of a modest revival at the US Open, after working with Connors in preparation for the tournament, both on site and in nearby Forest Hills.

She had lost 15 of 18 matches heading into New York.

Her ranking had plummeted to 25th from seventh.

But at the US Open, she posted three straight victories for the first time since January.

Concussions are a growing concern in many contact sports but are nearly unheard of in tennis.

In the 2013 Australian Open final, Li Na's left ankle gave out as she hit a backhand and she fell, hitting her head on the court.

A doctor tested her for a head injury, moving his finger in front of her face. Li successfully tracked it with her eyes until she started laughing.

Just like Bouchard's slip and fall, the few known examples of tennis players who had suffered a concussion also involved events away from the court.

At the 2010 US Open, a dizzy Victoria Azarenka collapsed 30 minutes into her match after suffering a mild concussion when she tripped on her sweatpants in warm-ups.

Her agent at the time, John Tobias, said she never considered not starting the match. "I think she felt it was just a headache," he added.

At a tournament in Charleston, South Carolina, in 2011, Lauren Davis suffered a concussion when lighting equipment fell on her.

She was waiting to be interviewed at a sponsor's tent.

Davis did not compete for two months and later sued the company which had installed the equipment for negligence.

NEW YORK TIMES