Title-holder Victoria Azarenka moved into the Australian Open second round on Tuesday but she made a meal of the match and looked far from her best in blazing conditions on Rod Laver Arena.
The second seed overcame world number 91 Johanna Larsson 7-6 (7/2), 6-2 but her game was riddled with unforced errors and poor serving, in contrast to Serena Williams' clinical first-round win late Monday.
The Belarusian took an hour and 46 minutes to get past the Swede as temperatures soared towards 43 Celsius (109.4 Fahrenheit). (Also read: Serena believes in having fun as she wins)
"It was a tough first set. The first match can often be tricky and the weather was not helping," said Azarenka.
"It was important to win that first set and I really found my rhythm in the second set."
Azarenka is searching for her third consecutive Melbourne title, a feat last achieved by Martina Hingis between 1997-1999.
In the Open era only five women have managed three in a row -- Margaret Court, Evonne Goolagong, Steffi Graf, Monica Seles and Hingis.
Despite being a two-time winner, the Belarusian is not favourite at the year's opening Grand Slam with that honour going to Williams, her conqueror in this month's Brisbane International final.
Larsson, despite being the Swedish number one and her country's only singles player present, had never gone beyond the first round at Melbourne Park in her three previous attempts.
In their only other meeting, the 25-year-old took just four games off Azarenka. But on Tuesday, Larsson caused problems.
She went 0-40 up on Azarenka's first service game but failed to ram home the advantage, with the world number two digging deep to hold and take the lead.
The Swede made it 1-1 and with Azarenka struggling with her serve, hitting three double faults in her first two service games, Larsson took her chance on her fourth break point when the second seed hoisted a forehand long.
The defending champion was agitated and started pumping herself up by shouting "C'mon!" as her trademark grunting became ever louder, which seemed to do the trick as she broke back to level the match at 2-2 and then comfortably held.
It went to serve till 4-4, in games riddled with unforced errors, before Larsson drew an overhit forehand from Azarenka to break for 5-4.
Fired up, Azarenka broke straight back before a backhand into the net handed the advantage once again to the Swede at 6-5. Another break in the 12th levelled it up before the tournament champion eased through the tiebreaker.
The fight went out of Larsson and Azarenka quickly raced to a 3-1 lead in the second. And after a Larsson double fault gave her a crucial second break for 5-2, she served out for the match.
The win sets her up with a second round clash against either Czech player Barbora Zahlavova Strycova.