Sharapova, seeded No. 2, made 51 unforced errors as she went for the lines, but saved some of her high-risk winners for when she needed them most. She faced two match points in the 10th game of the third set and ripped big forehand winners both times against Panova, a qualifier who entered the tournament without a single match win at five previous majors.
Sharapova, who won the 2008 Australian Open and has five Grand Slam titles, struggled with her serve in the second and third sets as the match extended to 2 hours 32 minutes in a temperatures topping 91 degrees.
"I'm just happy to get through — I was one point away twice today from being out of the tournament," Sharapova said. "I was not playing my best tennis today. I think she played a pretty inspired match. She came out here with not much to lose and swinging freely and going for her shots."
On the men's side, sixth-seeded Andy Murray of Britain didn't let the parochial crowds in Margaret Court Arena bother him as he beat Australia's Marinko Matosevic, 6-1, 6-3, 6-2. Matosevic's vanquished first-round opponent, Alexander Kudryavtsev of Russia, had accused boisterous fans of behaving like "animals."
After Wednesday's match, Murray laughed as he said: "It was a fun atmosphere to play today. Even if not everyone was supporting me."
Seventh-seeded Tomas Berdych advanced with a 7-6 (0), 6-2, 6-2 win over Austrian qualifier Jurgen Melzer. Berdych lost to eventual champion Stan Wawrinka in the semifinals last year at Melbourne Park.
Also Wednesday, Serena and Venus Williams withdrew from women's doubles, which they have won four times in Melbourne. A tournament official confirmed the sisters had pulled out but did not specify a reason. They were scheduled to play their first-round match Wednesday against Anabel Medina Garrigues of Spain and Yaroslava Shvedova of Kazakhstan.