Amid advice from officials that Melbourne residents stay indoors, practice matches for the Australian Open were suspended.
Main action at the Australian Open starts on January 20. Up one set and on the verge of levelling the second at 6 games apiece, Jakupovic collapsed to the court due to a reportedly "horrendous" coughing fit, before making the decision to retire after receiving medical treatment.
Matches were pushed back by an hour and play had been underway for a few hours before conditions again deteriorated, creating difficulties for some players.
The AQI in Melbourne as of early Wednesday local time was listed as 167 and categorized as unhealthy, according to the World Air Quality Index.
Seventeen fires were burning in Victoria on Tuesday evening. They still have time.
The country's environment minister Sussan Ley has warned that in some areas, koalas may have to be reclassified as endangered.
It's an obvious concern with the world's eyes set to be glued on Melbourne during the two-week championship, scheduled to begin Monday.
"I was really scared that I would collapse", Jakupovic told Australian Associated Press.
"But this is a new experience for all of us, how we manage air quality and therefore we've got to rely on those experts that advise us on how best to continue".
James Murdoch hit out at his father's media empire, which includes the News Corp group that dominates Australia's press landscape as well as Fox News in the United States, for climate change "denial".
The tournament has not changed its policy based on the day's events.
The conservative government led by Prime Minister Scott Morrison has also been heavily criticised by environmentalists and others for failing to do more to cut greenhouse gas emissions that are blamed for global warming.
Morrison has insisted his government is doing enough, and that he must protect jobs in the lucrative coal export industry.