Marathon Maria.

Maria Sharapova advanced to the semi-finals this evening after battling from down a set to defeat Alexandra Dulgheru, 3-6 7-6(6) 7-6(5). The back-to-back finalist from 2005-2006 advanced to her second consecutive WTA semi-final, having reached the same round of Indian Wells last week, and will face Andrea Petkovic, who advanced over Jelena Jankovic earlier this evening.

Dulgheru proved a fighter in the quarter-final match, but the No. 16 Sharapova defeated the Romanian in three and a half hours to continue her path towards her first final of the year. Although Sharapova had 17 double faults to Dulgheru’s four, she clipped 37 winners to just 15 in a telling difference of shotmaking ability.

Sharapova and Petkovic have met only twice, each winning one match, but Petkovic had the latest win, in the round of 16 at the 2011 Australian Open, where she defeated Sharapova in straight sets.

“It was long. It was tough,” Sharapova said. “It was not my best performance, but I gutted it out till the end. I didn't feel great throughout the match. I was making too many errors. My opponent was playing really well and consistent, and even though I had the lead, I just never took care of it. But at the end of the day I won, so I'm really happy.”

Sharapova rolled her ankle late in the third set and was attended to by the WTA physio. However, she said that she was confident of being fully fit for the semi-finals. “It hurt when I did it. I iced it a lot and did an ice bath and got it taped. I think I'll be okay. I'm tough.”