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."
In earlier second-round matches, No. 10
On the men's side, sixth-seeded
After Wednesday's match, Murray laughed as he said: "It was a fun atmosphere to play today. Even if not everyone was supporting me."