Slovenia's Dalila Jakupovic feared she would pass out during Australian Open qualifying with the smoky conditions the worst she's experienced.
The world no.180 was forced to retire mid-match at Melbourne Park on Tuesday due to the hazardous smoke lingering from bushfires in Victoria's east.
Jakupovic was leading her round one Open qualifying match against Switzerland's Stefanie Voegele when she collapsed to her knees with a coughing fit.
"I was really scared that I would collapse. That's why I went onto the floor because I couldn't walk anymore," Jakupovic said.
"I don't have asthma and never had breathing problems. I actually like heat.
"The physio came again and I thought it would be better. But the points were a bit longer and I just couldn't breathe anymore and I just fell on the floor."
The 28-year-old said she was having chest pains during practice, with the first day of qualifying delayed and practice suspended as Melbourne's air quality ranged from hazardous to poor.
Play eventually got underway at 11am - an hour later than scheduled - after the city's air was declared the worst quality in the world overnight.
An angry Jakupovic said it was "not fair" that officials asked players to take the court in those conditions.
"It's not healthy for us. I was surprised, I thought we would not be playing today but we don't have much choice," she said.
Former Wimbeldon finalist Eugenie Bouchard called multiple medical timeouts in the oppressive conditions as she survived to defeat China's Xiaodi You.
Her opponent also asked for medical assistance from the trainer and began regularly serving underarm in the third set.
Bouchard said she would train indoors on Wednesday because it wasn't "worth going outside" following her gruelling three-hour encounter.
"I felt like it was tough to breathe and a bit nauseous," Bouchard said.
"I felt like the conditions got worse as the match went on...but I was out there for a long time.
"As an athlete we want to be very careful, our physical health is one of the most important things. It's not ideal to play in these conditions.
"Just like the heat rule, there should be an air quality rule."
With only six days until the two-week championship begins, the world's eyes will be glued on Melbourne when thousands of international visitors converge on the precinct.
Health authorities expect the air quality to bounce between the "very poor to hazardous range" until at least Wednesday night.
Tennis Australia says it will work with their medical team, the Bureau of Meterology and Environment Protection Authority Victoria scientists when making decisions about whether it's safe to play.
"This is a new experience for all of us in how we manage air quality, so we have to listen to the experts," TA boss Craig Tiley said earlier on Tuesday.
"We have installed measuring devices on-site for air quality."
TA chief operating officer Tom Larner said any smoke stoppages would be treated in the same way as an extreme heat or rain delay.
"We will stop if conditions become unsafe based on medical advice," he said.
At the Kooyong Classic, players and officials decided to stop play between Maria Sharapova and German Laura Siegemund at 5-5 in the second set due to the smoke.
Novak Djokovic spoke out about the situation last week, saying organisers will be forced to create new rules to deal with smoke.
Australian Associated Press