Maria Sharapova cruises past Peng Shuai 
• Sharapova wins 6-4, 6-2 against world No20
• Victoria Azarenka beats Nadia Petrova to reach last eight
The defending champion Serena Williams went out at the last 16 stage after an epic struggle with ninth seed Marion Bartoli.
Williams, seeded seven, saved three set points in the first set and another four match points in the second but Bartoli held her nerve to win a high-quality match 6-3, 7-6.
Elsewhere it took Maria Sharapova about half an hour to find her range on Court No 2 but once she did it was like old times for the former champion as she battered her way into the quarter-finals with a 6-4, 6-2 victory over Peng Shuai of China.
The Russian served beautifully and thundered 27 winners as she moved into the last eight for the first time since 2006 – without losing a set so far this year. The world No1 Caroline Wozniacki is likely to be waiting in the next round and on this form the Dane's tennis shoes may just be squeaking a little.
"It's great. Last year I lost in the fourth round to Serena [Williams] and this year I find myself in the quarter-finals and giving myself an opportunity to go further," Sharapova said.
Wozniacki will have to get past Dominika Cibulkova first and in the early stages against Peng it looked as if Sharapova was in for a real battle. The world No20 was matching her from the baseline and when she got a look at a second serve, took her chances to attack.
The Chinese, who had equalled her previous best grand slam performance by reaching the fourth round, forced two break points in a long second game but Sharapova held. Games then stayed on serve to 4-4 when Sharapova finished off a great point with a pinpoint forehand volley on to the baseline to break.
Sharapova then served out for the first set and from then on it was completely one-way traffic as the Russian clicked into top gear, racing to a 4-0 lead thanks to two breaks. She lost just five points on her first serve in the whole match and though Peng held a couple of times, it was too little too late.
The Russian duly wrapped up victory after an hour and 21 minutes with another thunderous forehand. The bookmakers made her the second favourite before a ball was struck last Monday but the 2004 champion said she still had "to be realistic". "I hadn't got past the fourth round in several years but this is a step forward," she said. "I just have to take care of business in my next match."
Also into the last eight is the fourth-seeded Victoria Azarenka, who looked in imperious form as she dispatched Nadia Petrova.
Azarenka just edged past Petrova in a meeting between the pair here two years ago, but the 21-year-old made light work of her opponent on Court No3 this time around, winning 6-2, 6-2 to set up a quarter-final with either Tamira Paszek or Ksenia Pervak.
The result seemed unlikely at the start of the match as Petrova held to love before breaking Azarenka's serve with a composed backhand to move 2-0 up. That was to be the last game Petrova won for a while though, as Azarenka produced winner after winner, breaking her opponent's serve three times before taking the first set when the Russian cleared the baseline with a backhand.
It was much the same story in the second set as Azarenka pinned Petrova on the baseline in the first game, causing her opponent to plant into the net and lose another service game. Petrova then held serve for just the second time, but Azarenka broke in the fifth game to move 4-1 up in the second set.
The Belarusian then survived a rare break point before serving out to seal victory in just an hour and three minutes.
