The scalding sun that harassed Maria Sharapova throughout the longest match of her career was obscured by a curtain of clouds today. As she took the court to face Alize Cornet, the temperature was about 35 degrees cooler than the 111-degree inferno Sharapova survived Thursday. But midway through the second set, Sharapova sat wrapped in an ice vest, dripping with sweat while her once commanding lead melted away.

Sharapova would keep cool. She blazed through the opening set but went cold for stretches of the second before finally sealing a 6-1, 7-6 (6) victory to advance to the Australian Open fourth round for the eighth time.

It was a wildly uneven performance from Sharapova, who is still trying to shake off the rust from injury-induced inactivity that’s limited her to nine matches since Wimbledon. The 2008 champion suffered some service breakdowns—she served just 50 percent, hit eight double faults, twice failed to serve out the match, and caught several errant tosses—scattered 35 unforced errors, and had to stave off a set point at 5-6 in the second-set tiebreaker. Yet despite some unsightly patches, a few frustrated glances toward coach Sven Groenefeld, and the complications she created by spraying shots, Sharapova managed to put enough deep drives together to prevent another adventure.

Blasting a cross-court backhand winner that struck the sideline, Sharapova opened with a love hold and proceeded to pound out three consecutive breaks, surging to a 5-1 lead. The weight of Sharapova’s baseline blasts buckled Cornet’s knees, leaving her looking like someone blown backwards while trying to slam a steel door shut in the face of a wind gust. Sharapova closed the 32-minute opening set on the strength of 11 winners compared to her opponent's four, reducing Cornet to burying her face in her towel as if wiping away the horror show of a first set.

When Sharapova couldn’t convert a triple break-point chance at 1-all in the second, it infused Cornet with new life. The 25th-seeded Frenchwoman hit a fine backhand drop volley winner to break for 3-1. Sharapova responded by breaking at love and reeling off four straight games for a 5-3 lead. At that point, the end seemed imminent. But Sharapova stumbled when she served for the match at 5-4, missing a backhand down the line on match point and dumping two double faults to drop serve. She failed to serve it out again at 6-5, after which things got tense and a little ugly.

Cornet was set up for an easy smash at the service line, but bungled it, bashing the ball into the court while falling down to give Sharapova a 3-2, mini-break lead. But the Russian's forehand betrayed her, and when she sailed a forehand deep, Cornet had a set point. Sharapova saved it with a swing volley, belted a backhand return to earn her second match point—29 minutes after her first one—and finally closed on a Cornet error.

The former No. 1 knows she must step it up significantly against a familiar foe, Dominika Cibulkova, who has roared through the draw, dropping just nine games in three victories. Sharapova has won three of their five meetings, but Cibulkova crushed Sharapova, 6-0, 6-2, in the 2009 Roland Garros quarterfinals.