The darling of Edgbaston Priory Maria Sharapova slipped through the gears and into the quarter-finals yesterday with a comprehensive straight-sets win over China's Na Li.

The 19-year-old's 200th senior victory came via an accomplished performance in which she overpowered her opponent and played the big points significantly better.

That is not to say Li was a willing conspirator in her own downfall. The world No 32 battled hard against the reigning DFS Classic champion and although she didn't have any more success on the scoreboard than Sharapova's previous victim, Ahsha Rolle, she was much more involved in each point.

The 6-2, 6-4 scoreline, a mirror image of Wednesday's result against Rolle, did not really reflect the difference in quality of display put in by Sharapova.

She noticed it herself, though: "I played a lot better match than I did in the first match," Sharapova confessed.

"The conditions were definitely more comfortable. I felt I could hit the ball, my movement was a lot better and I felt like I could get grip on the court."

She also upped the tempo when it looked as though Li could stretch her into a third set after breaking serve in the eighth game of the second.

However, tied at 4-4, Sharapova manufactured three break points, the third of which was converted with a sumptuous forehand pass down the line, punishing Li for making a rare venture to the net.

To the relief of everyone on centre court the former Wimbledon winner's serve did the rest as she closed out in the next game. "She definitely made me work for it," Sharapova said.

"I had a little bit of a let down in the second when she broke me but it stayed pretty tough. I was able to play a good point on break point which was a big moment in the match."

The biggest positives to come out of the afternoon were the place in the last eight and a burgeoning confidence in her own physical fitness.

Having had her French Open campaign undermined by a foot injury the world No 4 now seems to be moving freely and reasonably comfortable with the situation. All that bodes well for her prospects at the All England Club in ten days' time.

Her progress in the top half of the draw has been marked by Italy's Francesca Schiavone in the bottom.

The Italian world No 14 is second seed here, despite a pretty poor grass court record and has never made it past the third round at Wimbledon.

Which is exactly why she has come to Birmingham in a bid to familiarise herself with the surface under the watchful eye of Martina Navratilova.

The American is helping Schiavone with her game this week and there were certainly signs that her input is having an effect as she showed little hesitation in coming to the net against Tsvetana Pironkova.

The Bulgarian won the first set but was eventually out-thought by her opponent who went on to win 3-6, 6-3, 6-1.

"It was hard work but an important win," Schiavone said. "I have to play a lot on grass because it is not my surface. I am trying to get a feel for it and be more comfortable not like last year or two or three years ago when I went directly to Wimbledon. That's not easy."

Sania Mirza's run came to a shuddering halt against Meilen Tu in a match which featured an incredible 17 service breaks. The Indian, potentially a top grass court player, crashed out 2-6, 6-4, 7-6 after losing her nerve in the deciding set.

Other third round winners were Mara Santangelo, Jamea Jackson, Elena Likhovtseva and Vera Zvonareva. Sharapova now meets Santangelo, Likhovtseva faces Jackson and Schiavone takes on Zvonareva.