Maria Sharapova booked her place in the semi-finals of the Sony Open in Miami with a straight-sets win over Italy's Sara Errani.

Sharapova prevailed 7-5 7-5 despite turning in an error-strewn display, the third-seeded Russian racking up almost 60 unforced errors and committing 13 double faults.

Fortunately for Sharapova, who saved three set points in the second, Errani did not have the weapons to take advantage and she did just enough to set up a last-four encounter with 22nd seed Jelena Jankovic.

"Sara is extremely difficult to play," Sharapova told

"She doesn't have the height or the power, but she gets so many balls back and stays so consistent, and does it over and over again.

"She is so consistent. She also has great court coverage and variety. She really makes you work.

"She can do a lot of things with that court coverage and variety when she has time, so my success in the beginning of the match and in some other points was when I didn't give her that opportunity.

"But most of the time I did, and that's why she kept coming back and kept playing really well out there.

"I feel very lucky that I'm through. She had her chances to win that second set - who knows what would have happened. I'm lucky to get to the next one and have a chance to be in the semis again."

Sharapova is bidding for her first win at the Florida event after four previous runner-up finishes, including back-to-back final defeats in each of the last two years.

Standing in her way in the last four is Serbia's Jankovic, who beat another Italian, Roberta Vinci, 6-4 6-7 (6/8) 6-3.

In the men's draw, third seed David Ferrer came from a set down to beat Jurgen Melzer 4-6 6-3 6-0 and set up a semi-final with Novak Djokovic's conqueror, Tommy Haas.

Ferrer dropped the first set despite going up a break, but was in control from there - particularly in the final set as he broke three times and dropped just four points on serve.

"I was a little bit nervous in the first set and part of the second," Ferrer told "But I tried to fight every point, to be focused and I had a good feeling in the final of the second set and of course in the third one."

In his third Miami semi-final, he will face veteran German Haas who followed up his win against Djokovic with a 6-3 6-1 win over Gilles Simon.

The remaining two men's quarter-finals, including Andy Murray v Marin Cilic, take place later today.