A half-hour into her Round of 16 match on Monday afternoon, Eugenie Bouchard began to feel light-headed. By the second set, her vision had begun to blur.
After three rounds of struggle at Flushing Meadows, Bouchard was finally struggling against something she couldn't will herself past – the heat.
After the high of the Wimbledon final, Bouchard staggered through her hard-court season. She was nicked up. She wasn't able to practise. Her form flagged. She arrived here trailing doubt like a string of tin cans.
"I didn't have the highest expectations for this tournament," Bouchard said after losing to Russian Ekaterina Makarova 7-6(2), 6-4.
That didn't stop the rest of us from assuming them on her behalf.
Throughout the first week, big names on the women's side fell hour by hour. Bouchard wasn't playing particularly well, but her draw was lining up nicely. By Monday, she was one of only two top-eight seeds remaining.
All her new fans worried she lacked sharpness. As it turns out, she was instead missing the sort of fitness that can only be reached with regular match play.
That, combined with the conditions, did her in.
How to describe the midafternoon heat on Monday? Crushing. Withering. The sort of heat that makes you want to give up hope. It was the heat that precedes a riot.
One of the brave souls who sat through the entire tilt at Louis Armstrong Stadium announced after the match, "I've sweat through my skirt."
And none of us was moving. We were all trying to channel lizards – survive through stillness.
It was 32 C at the outset, but it was the humidity that made you want to weep. You haven't really felt humidity until you've felt it in New York. It's the reason the whole city is given over to tourists for the month of August.
The combination of high temperatures and fatigue has claimed several players over the first week, but these were easily the most will-sapping conditions yet. An hour in, both players had taken on the colouring of boiled meat.
Bouchard flinched first, calling a medical timeout halfway through the second set. The venue medic took her blood pressure while she guzzled water and energy drinks. As the physio massaged Bouchard's extremities, Makarova sat alongside her with a bag of ice balanced on top of her head. You could actually see it melting.
Doctors treated Bouchard for two hours after her match, draping her in ice-filled towels. By the time she came out to talk to the media, she still appeared woozy.
She probably should have given up. Makarova was the first opponent she met here who could reliably spray the ball to the edges of the court. Bouchard was forced to run, the fight palpably draining out of her.
She should have quit, but she wouldn't.
"I never want to retire from matches," she said, "no matter what."
Afterward, though plainly gutted, she was due a bit of self-congratulatory reflection on the year gone by. The women's game is roiled by inconsistency. Coming into the day, 24 different competitors had made the quarters of a Grand Slam this year.
Amidst all that chaos, Bouchard's consistency stood out. Only she and Maria Sharapova made the fourth round at every Slam.
The strange thing about consistency – you start getting used to it. Bouchard has been so good, we've forgotten how quickly this all came together. Two years ago, she was a junior here at the U.S. Open. Last year, she got to the second round, completely anonymous.
This year, she was a bold-faced name on arrival, one of the crowd favourites. No Canadian woman had ever played a night match in the cavernous Arthur Ashe Stadium until this year. Bouchard did it twice.
You couldn't help but feel for poor Makarova on that score. The near-capacity crowd was fully behind the Montreal starlet. When it ended in the Russian's favour, they seemed resentful.
Bouchard didn't feel like congratulating herself – "This year is not over … I don't want to look back and do a kind of recap" – so we'll have to do it for her.
This kid – and that's what she is at only 20 years old – is both the present and the future of Canadian sport. She will continue to grow into her game. All the talent is already there. All she requires is the level of conditioning and cunning that only comes with time.
Experience is the only steady factor amidst all the up-and-down in the women's game. Over the past two years, the average age of a women's Grand Slam winner is 28. For men over a similar span, it's 26.
Considering that, what Bouchard has managed throughout this year is more than remarkable. It's resetting tennis's baseline.
The breakthrough has already happened. But everything about what Eugenie Bouchard has done to this point suggests there are several more ceilings for her to crash through.