Top-seeded Agnieszka Radwanska of Poland extended her unbeaten start to the season to six matches with a 6-4, 6-3 win Tuesday over 42-year-old Kimiko Date-Krumm at the Sydney International.
Radwanska, who won last week's WTA tournament at Auckland, New Zealand, coped as best she could with the searing 40 degree Celsius (over 100 degrees F) temperatures at Olympic Park and secured an early break over the veteran Japanese player.
''This is too hot to play tennis,'' Radwanska said when asked whether matches should be put on hold at the Australian Open lead-up event. ''Even for players, for ball kids, for the people sitting out there, it's just too hot.''
Radwanska said she was trying not to alter her game in the conditions but admitted she had more of a battle against the heat than her opponent.
''The first main thing is just to stay calm and trying to survive,'' said the 2012 Wimbledon finalist, who admitted having experienced similar conditions at Melbourne Park during the Australian Open.
The Sydney 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.
Elsewhere, third-seeded Sara Errani of Italy and fourth-seeded Li Na of China easily advanced to the quarterfinals.
Errani beat Russian Maria Kirilenko 6-1, 6-1. Li, who was pushed to two tough sets in beating American Christina McHale in the first round on Monday, dominated Ayumi Morita of Japan 6-1, 6-0.
In first-round men's play Tuesday, sixth-seeded Radek Stepanek of Czech Republic defeated Guillermo Garcia-Lopez of Spain 6-2, 6-3 and Spain's Feliciano Lopez beat seventh-seeded Jeremy Chardy of France 6-7 (2), 7-5, 6-3.
Jarkko Nieminen of Finland defeated qualifier Bjorn Phau of Germany 6-0, 6-1 and Australian wild-card entry John Millman beat Spain's Tommy Robredo 6-3, 6-4.
Top-seeded John Isner of the United States, who received a first-round bye, will play his second-round match on Wednesday against the winner of Tuesday's later match between American qualifier Ryan Harrison and Spain's Roberto Bautista Agut.