A player collapsed in a coughing fit and retired from Australian Open qualifying on Tuesday as organisers faced a storm of criticism for ploughing ahead with matches despite bushfire smoke plunging Melbourne's air quality to "hazardous" levels.
Slovenia's Dalila Jakupovic was leading Stefanie Vogele 6-4, 5-6 at Melbourne Park when she slumped to her knees at the back of the blue hardcourt suffering breathing difficulties.
Twenty-eight people have been killed and thousands made homeless in recent months as huge fires across the country have scorched 11.2 million hectares (27.7 million acres), nearly half the area of the United Kingdom.
Jakupovic, 28, told reporters she was fighting for breath.
"I never experienced something like this and I was really scared," she said.
"I was scared that I would collapse. That’s why I went on the floor [of the court] because I couldn’t walk any more. When I was on the ground it was easier to get some air.
"It's not healthy for us," she added. "I was surprised, I thought we would not be playing today but we don't have much choice."
Her retirement came only hours after tournament director Craig Tiley defended the decision to proceed with qualifiers after they were initially delayed due to the poor air.
"During the period of when we suspended practice and restarted the matches there was an improvement in the conditions," Tiley told reporters before Jakupovic's retirement.
The pollution prompted warnings from Victoria state's environment watchdog for people to stay indoors, bring pets inside and shut windows.
Tennis officials have said there is little chance of the Australian Open being delayed, but that air quality is being monitored and umpires can halt matches to protect players' health.
Practice on outside courts was suspended but big-name players including world number one Rafael Nadal were not affected, with their hit-outs going ahead on Rod Laver Arena with the roof closed.
Australia's weather bureau said there was widespread smoke across central and eastern Victoria state, including Melbourne, which was expected to clear by Wednesday afternoon.
Players woke to a pea-soup haze blanketing Melbourne, prompting Ukraine's world No 5 Elina Svitolina to post a graphic of Melbourne's "very unhealthy" air measured by the World Air Quality Index, a global monitor, on Twitter.
"Why do we need to wait for something bad to happen to do an action," she tweeted.
Mandy Minella, the world No 140 from Luxembourg, said she was "shocked" that qualifying was allowed to take place.
"What about the health of all the people that have to work out there, especially the ballkids?" she tweeted.
Victoria's chief health officer Brett Sutton told local media the air quality in Melbourne had been the "worst in the world" overnight.
Former world No 1 Maria Sharapova's warm-up match at the Kooyong Classic in Melbourne's eastern suburbs was abandoned with the Russian trailing Germany's Laura Siegemund 7-6, 5-5 after both players complained to the chair umpire.
Five-time Grand Slam champion Sharapova said she felt a cough coming on in the second set.
"After two-and-a-half hours that was the right call for me. I think both of us felt it," she told reporters.
Authorities expect the smoke to linger until Wednesday when afternoon showers are forecast.
Australian Open men's champion Novak Djokovic expressed concern earlier this month that bushfire smoke might cause health problems for players.
Tournament organisers said last week that play would be confined to Melbourne Park's three roofed stadiums and eight indoor courts in the "unlikely case of extreme smoke conditions".
Tiley said last week it was unlikely that the Grand Slam would be delayed, regardless of the conditions.
Any smoke hazards will be treated in a similar way to extreme heat and rain, with umpires able to stop play if it is considered too dangerous to continue.
Several sports events have fallen victim to thick smoke since the fires first ignited, including last month's SOLAS Big Boat Challenge in Sydney and a Big Bash cricket match in Canberra.
But dozens of other fixtures have gone ahead.
Leading tennis players and other sports stars have been quick to respond to the crisis, pledging money to relief efforts.
Roger Federer, Serena Williams and Nadal are set to headline a fundraising exhibition at Melbourne Park on Wednesday.