Maria Sharapova upset by emotional Flavia Pennetta at Indian Wells

Maria Sharapova couldn't overcome her erratic play in the fourth round at Indian Wells, falling victim to an upset at the hands of defending champion Flavia Pennetta.

INDIAN WELLS, Calif. — Defending champion Flavia Pennetta overcame an erratic Maria Sharapova and her own emotions to beat the No. 2 player 3-6, 6-3, 6-2 and advance to the quarterfinals of the BNP Paribas Open. 

No. 16 Pennetta, a surprise champion last year, won back-to-back matches at just four regular-season tournaments after that win. But she came into Tuesday's match 2-2 against Sharapova, having won their last two matches. This was their first meeting since the 2011 U.S. Open, which the Italian won 6-3, 3-6, 6-4. Pennetta will play either Caroline Garcia or Sabine Lisicki for a spot in the semifinals.

Watch: Davenport applauded in first on-court coaching timeout with Keys

​Sharapova's patterns, particularly her hard crosscourt backhand, feed right into Pennetta's strength. “​I think I have the good backhand, and with her she plays normally like the crosscourt really, really fast,”​Pennetta said. “​Most of the players don't take the first two or three shots with her. For me, [it] was easy. I mean, my backhand is the good shot, the natural shot that I have.

“So the game she plays with me, it's a good game for me. She don't make a lot of pressure in the way she's supposed to play. But with the backhand, the crosscourt, for me, it's really easy to just stay there and play one more, one more, one more.”

• NGUYEN: Serena comes back to defeat Stephens, reach quarterfinals

Sharapova started the match well but the errors began to creep in after the first set. Pennetta was dealing with her own troubles, leaving the court in tears after the first set when she took a bathroom break. Pennetta chalked it up to the expectations of playing Sharapova with a title defense on the line finally getting to her. 

“In the beginning I was O.K., because for the first two or three games I was O.K.,” Pennetta said. “Then [the emotions were] coming. Like I never expect. I never do something like that. It just was the first time. I think I handled [it] pretty good, because normally you go away and you don't want to stay on the court. But for me [it] was important to just keep calm and try to play. In the end I just played really well.”

Serena shows resilience in virtuous return to Indian Wells after 14 years

Play well she did. Pennetta began reading Sharapova's patterns and anticipated her placement and handled her pace. As the Italian's defense shrunk the court, Sharapova began to misfire. She hit 42 unforced errors in the match, 11 of which were double-faults. 

“Definitely had some chances in the beginning of the second set,” Sharapova said. “A few Love-40, Love-30 games. Just didn't commit enough. Didn't take one of those. I think she gained a little bit of confidence after that. She started feeling a little bit kind of fresh breath of air, started going a little bit more for her serve, for the lines.”

“I just felt she got in a really good rhythm,” Sharapova added. “Everything I gave her she was able to hit back solid with pace. She mixed it up. She was seeing the ball a lot better.”​ Pennetta finished with 15 winners to 34 unforced errors. Sharapova hit 27 winners to her 42 errors.

Sharapova said she will take a day off and then get back on the practice courts to prepare for next week's Sony Open.