Former world number two Svetlana Kuznetsova defied sweltering heat that earlier prompted Agnieszka Radwanska to suggest it was too hot to play to beat seventh seed Caroline Wozniacki on Tuesday in the second round of the Sydney International.
Russia's Kuznetsova, a two-times grand slam champion who was knocked out in the first round in Auckland last week and had to qualify for the main draw in Sydney, beat the former world number one 7-6 1-6 6-2 in a match that lasted almost four hours.
Sydney had been forecast to hit a maximum of 43C on Tuesday as Australia swelters in a heatwave that has sparked raging bush fires.
The Australian Bureau of Meteorology reported a temperature high of 41.4 C at 1530(local) at Sydney's Olympic Park and top seed Radwanska had said earlier that play should have been abandoned until the temperature dropped.
The world number four, who was given a bye into the second round, played the opening match on centre court and beat Japan's Kimiko Date-Krumm 6-4 6-3 to advance to the quarter-finals but even that early in the day the heat was effecting the players. "I think this is too hot to play tennis," Radwanska said. "Even for players, for ball kids, for the people sitting out there, I think it's just too hot."
Li Na, who beat Japanese qualifier Ayumi Morita 6-1, 6-0, said she was reaching for the ice towels at each changeover.
"I was feeling like playing in a sauna. At the first changeover I didn't use an ice towel. I was feeling the heat was coming and I was like, 'What's going on'?" Li said.
"At the next changeover I was like, 'OK, I need an ice towel every changeover, otherwise I don't know how to play on the court'.
"It's too hot, but I'm still in the tournament, so it's good news."
The tournament has an extreme heat policy but it only comes into effect at the discretion of the tournament referee.
Tennis officials apply a complex formula factoring in heat, humidity, and wind to determine when on-court conditions become too stressful for the players.