Caroline Wozniacki moved to within two wins of regaining the world number one spot from Kim Clijsters - but only reached the last 16 of the Dubai Open after her opponent, Anna Chakvetadze, suddenly and dramatically fainted.
One moment the former world number five from Russia was standing behind the baseline, preparing to serve, and the next she was spreadeagled on the court.
A doctor, a trainer, the umpire and Wozniacki all rushed to help Chakvetadze, and after a seven-minute delay in which her blood pressure was checked, she played one more point before retiring with the score at 6-1, 3-5 and 40-15.
"It was a shock," said Wozniacki. "It was scary. She is a good friend of mine, but to see anyone collapse on the other side of the net is not a good sight. It was quite a surprise."
It was less of a surprise for those who had seen how sluggish Chakvetadze had been while somehow getting past Daniela Hantuchova the previous day, or those who noticed how poorly she looked between points.
It was remarkable that she even tried to play one more rally after her fall. It had taken five minutes before she was able to get up, and after being helped to the bench, she still looked too weak to do much.
One fault and one tepid serve was all it took for her to be convinced of this, and after a hug from Wozniacki she was taken away for further treatment. She was diagnosed with a gastro-intestinal illness.
It was therefore all the more creditable that Chakvetadze progressed to within sight of winning the second set after losing the first limply in only 23 minutes. It was such a turn-around it even made Wozniacki throw her racket in frustration, a rarity for her.
"The first set was so short I didn't get into the match too much," Wozniacki explained. "She was making so many mistakes and I didn't get any rhythm.
"Then suddenly she started to go for it and I needed time to get back. I had only just started to play better towards the end."
Wozniacki now plays Ayumi Morita, a Japanese qualifier who disappointed the organisers by removing arguably the tournament's greatest draw, Sania Mirza, the Indian star now based in Dubai.
Mirza, who says she is no longer hurting after being injured for much of the last two years, was nevertheless not at her best in a 6-4, 6-2 defeat.
She had made her mark the day before, however, when she said that after a year of nuptials she "still didn't feel married, so I guess that's a good thing".
The comment brought laughter, and required clarifying, which Mirza quickly did. "I mean we feel like it's pretty new, we feel like it's pretty new," she stressed.
"He's here for a few days which is really good," she hastily added, to emphasise that all was well with her and her test cricketer hubby from Pakistan, Shoaib Malik.
Earlier Svetlana Kuznetsova earned another meeting with Francesca Schiavone, with whom she played the longest women's match in Grand Slam history last month at the Australian Open.
Then Kuznetsova lost in four hours and 44 minutes. Now former US and French Open champion won a two-hour 30-minutes tussle with Tavetona Pironkova by 5-7, 6-2, 6-3 to earn a chance of revenge.
"I think every single person who knows me watch that match in Melbourne came to me and said it was a great match," Kuznetsova said.
"This is going to be another very hard match - but I have nothing to lose. She's the favourite. The pressure is on her this time."