Poor air quality caused by ongoing wildfires has forced one player to retire from her match and delays during qualifications at the Australian Open.
Dalila Jakupovic retired at 6-5 5-6 against Switzerland's Stefanie Voegel, the Slovenian helped off the court in Melbourne after collapsing during a coughing fit.
Smoke haze caused by wildfires led the organisers to temporarily suspend practice sessions for the tournament on Tuesday, with qualifying beginning later in the morning following a delay.
"Further decisions will be made based on onsite data, and in close consultation with our medical team, the Bureau of Meteorology and scientists from EPA Victoria," a statement from organisers said.
"As always the health and safety of our players, our staff and our fans is our priority."
"We have experts who analyse all available live data as specific to our sites as possible and consult regularly with tournament officials and, in the case of heat and smoke, medical experts."
Victoria's Environment Protection Authority had warned that air quality in the state - of which Melbourne is the capital - would range from moderate to hazardous because of wildfires that have been raging for months both in Victoria and the neighbouring state of New South Wales.
Players affected by the delayed start to qualifying include Australia's former number one male tennis player, Bernard Tomic, and the Canadian Eugenie Bouchard, a finalist at the 2014 Wimbledon Championships.
Australian Open tournament director, Craig Tiley, said last week that he was hopeful the tournament would go ahead but said air quality would be closely monitored.
"We have committed substantial extra resources to analysis, monitoring and logistics to ensure the health and safety of all players, staff and fans throughout the summer and have no other plans to move events (following the cancellation of an event in Australia's capital Canberra)," Mr Tiley said in a statement.
"Assessing the likelihood of smoke-induced interruptions is a bit like how we treat heat and rain.
"We have experts who analyse all available live data as specific to our sites as possible and consult regularly with tournament officials and, in the case of heat and smoke, medical experts.
"We have access to real-time monitoring of air quality at all of our venues and are working closely with medical personnel and local experts onsite to ensure we have the best possible information available to make any decisions regarding whether play should be halted at any point.
"The health of players, fans and staff is a priority at all times and we will continue to make these decisions with that in mind."