New York - China's Zhang Shuai apologised for knocking her best friend Samantha Stosur out of the US Open on Thursday, hailing the former champion for talking her out of quitting the sport last year.
Zhang eased to a 6-3, 6-3 second round win over the 2011 US Open winner but said she had wished the two friends, who are also doubles partners, had faced each other later in the tournament.
"Everyone knows we are good friends, we train together a lot of the time. When we came to New York, we practiced together at the same time on this same court," said the 27-year-old after her 70-minute win on the new Grandstand.
Zhang revealed that Stosur convinced her not to quit tennis when they met for a meal in Beijing last year. At the time, she was at 186 in the world rankings.
The chat seemed to work as just a few months later Zhang reached the Australian Open quarter-finals, ending a sorry-looking 0-17 record at the majors.
"She helped me a lot last year when I thought about retiring. She told me to keep going and not give up. She tried to help me by playing doubles.
"It's a tough feeling playing her and I feel sad for Sam. She always tries her best, she loves the game. I hope that next time we will meet later in the tournament."
Zhang, now ranked 51st, had lost to Stosur in the second round of the French Open in May.
"I didn't think I could beat her, it's very hard to defeat a former champion," said Zhang after seeing off the 16th seeded Australian.
Zhang is the only Chinese player left in the singles draw in New York. She goes on to face Yaroslava Shvedova of Kazakhstan for a place in the last 16.
Win or lose, she has achieved her best result already at the season's last Grand Slam.
She lost in the first round in 2008, 2011 and 2014 and failed to get out of qualifying on six other occasions.
"I am very excited. I love New York. Now I want to focus on my tennis and not on the fact that I am the last Chinese woman left in the competition," she said.
Zhang's win on Thursday was the first time she had claimed back-to-back victories since Indian Wells in March.
Meanwhile, Zhang and Stosur will be on the same side of the net on Friday when they face Russia's Elena Vesnina and Ekaterina Makarova in the second round of the women's doubles.