The decibel level went up a notch at Wimbledon [Images] on Tuesday as defending champion Maria Sharapova [Images] moved ominously into the semi-finals.

After four rounds of gentle sparring, the 18-year-old Russian was given a real battle early on by compatriot Nadia Petrova on Court One before emerging victorious 7-6, 6-3.

"It was a tough match ... it sends shivers down my body to be in the semi-finals again," she said, after securing a last four showdown with Venus Williams [Images], who withstood a second set fightback to beat Mary Pierce 6-0, 7-6 and reach her fifth Wimbledon semi-final.

While second seed Sharapova huffed and puffed and bristled with intensity, Amelie Mauresmo was a study in graceful athleticism, bounding past Russian Anastasia Myskina [Images] 6-4, 6-3.

The battle-weary Myskina, who had saved match points in the two previous rounds, was no match for Mauresmo's mesmeric all-court game, losing for the sixth time in seven meetings.

"I really wanted to be aggressive in this match and that's what I did from the first point," said Frenchwoman Mauresmo.

The third seed will meet top seed Lindsay Davenport [Images], who beat U.S. Open champion Svetlana Kuznetsova [Images] 7-6, 6-3, in her third semi-final in her last three visits to the All England [Images] Club.

Sharapova has become a worldwide brand since her stunning triumph against Serena Williams [Images] in last year's final -- she has even just launched her own perfume.

When she walks out on court, however, the multi-million dollar smile is replaced by the scowl of a streetfighter.

The athletic Petrova, who saved two match points on Monday against Czech Kveta Peschke, was not about to be intimidated by the queen of grasscourts.

Five years older than Sharapova she showed scant regard for the world number two's reputation as she match her opponent blow for blow in the first 12 games.

Sharapova thrives on pressure, however, and she found her best tennis of the match in the tiebreak. Shrieking louder with every swiping forehand, she moved into a 6-4 lead.

Petrova refused to blink and saved both set points, but when Sharapova earned another set point she hammered an unstoppable forehand past the eighth seed.

Sharapova hurtled into a 3-0 lead in the second set and although Petrova never let her out of sight she was dealt a cruel blow when trailing 5-3.

Facing a break point Sharapova got lucky with a forehand that rolled off the tape and dropped dead. Another netcord gave her match point and Petrova obliged by wafting a forehand long.

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