New York - Canada's Eugenie Bouchard suffered a head injury when she slipped and fell in the US Open locker room, forcing her out of women's and mixed doubles and jeopardising her fourth-round singles match on Sunday.
The 21-year-old from Montreal sustained the injury late on Friday and she agreed with medical staff advice to withdraw from two doubles matches set for her on Saturday.
"The severity of the injury was and continues to be assessed by the on-site medical personnel at the US Open," US Open tournament director David Brewer said.
"No determination about competing in the singles competition has been made at this time. Ms Bouchard will continue with medical evaluation and treatment."
Bouchard was playing alongside Australian Nick Kyrgios in mixed doubles and Russia's Elena Vesnina in women's doubles and had taken special pride Friday in being the only woman remaining in all three events at the US Open.
Bouchard, seeded 25th, is set to face Italy's Roberta Vinci in the fourth round.
It's a rematch of the first round at New Haven two weeks ago when Vinci rolled 6-1, 6-0, a defeat that inspired Bouchard's US Open run.
"I think my loss was kind of a shock to me, a little bit of a wake-up call in a sense I had to get my act together a little bit," Bouchard said after her third round win over Dominika Cibulkova on Friday.
The latest setback has been part of a year of struggles for Bouchard, who reached last year's Australian and French Open semi-finals and the Wimbledon final, losing to Czech Petra Kvitova, as well as collecting her first WTA title at Nuremberg.
After a quarter-final run this year at the Australian Open, Bouchard dropped her first matches at Roland Garros and Wimbledon and is only 12-17 on the season.
She had not won consecutive matches since March until this week.
But Bouchard has battled back with help from tennis legend Jimmy Connors, who works as an advisor and was set to watch her for the first time in their partnership on Sunday if the match takes place.
"Working with Jimmy has really given me a different side of things, like a different point of view," Bouchard said before her fall.
"He's very energetic. He's kind of lifted my spirits a little bit. He believes in me. He helped me kind of believe in myself more and regain that confidence. That has helped me."
The 63-year-old American, a five-time US Open winner and eight-time Grand Slam champion whose last major trophy came at the 1983 US Open, bolstered Bouchard's confidence.
"He said, 'You're too good to be having the results you're having,'" Bouchard said of Connors. "He has definitely helped me in my time of need."
Connors, whose last Grand Slam event was the 1992 US Open, made an epic 1991 US Open semi-final run at age of 39. The mental and physical fortitude needed for such a run is something Bouchard needs now.
"He has so much experience. Just hearing his stories and listening to him speak, I respect him so much," Bouchard said.
"I think he was great mentally when he played. Just the little tips and advice he would give me. The fact that he told me he truly believes in me reminded me, 'Hey, I need to believe in myself as well.' We just needed to build up my confidence a little bit."