Australian Open organisers have imposed a two-hour delay to the start of qualifying matches on Wednesday because of the “very poor” air quality from ongoing bushfires in the country.
It is the second successive day the start of play has been delayed because of the conditions in Melbourne.
On Tuesday, Slovenia’s Dalila Jakupovic had to be helped off court after retiring from her match.
Air quality in the city did improve overnight but is still “unhealthy”.
Play will now begin at 12:00 local time (01:00 GMT).
According to the Environment Protection Authority in Victoria, the forecast is for improving conditions on Wednesday with a chance of a storm.
At least 28 people have died and an estimated 10 million hectares (100,000 sq km) of land in Australia has burned since 1 July.