MELBOURNE, Australia — Maria Sharapova toiled in 43-degree Celsius (109 F) temperatures for more than 3 1/2 hours on Rod Laver Arena and could count herself among the unlucky early starters at the oppressively hot Australian Open on Thursday.

The temperature was 39 C (102 F) when Sharapova’s match against No. 44-ranked Karin Knapp started just after 11 a.m. local time. It increased to almost 43 C by the time she finished off a 6-3, 4-6, 10-8 win on her fourth match point, 50 minutes after her first. It was the longest women’s match so far in the tournament.

At the height of the heat, Sharapova, dripping in sweat, wasted three match points on serve in the 10th game of the third set.