Hawk-eyed Sharapova sets up rematch

Maria Sharapova has reached the last 16, but on the evidence of this match – against a dogged unseeded opponent – she will have to up her game when she meets the defending champion, Serena Williams, in the next round. The Russian is recovering her form after the shoulder surgery in 2008 that necessitated the rebuilding of her serve, but had a stuttering start to her match against the Czech Barbora Zahlavova Strycova and opened with a double fault.

Sharapova dropped her first two service games and it was not until her driving forehand started working that she seemed to settle into the match. But her multi-syllabled opponent made her work for every point and was more willing to come to the net and, although she misjudged some drop shots, managed to pass the former champion with ease several times. But after 64 minutes, the Czech double-faulted on a break point to lose the first set 7-5.

If her game was not entirely on song, Sharapova's eye was certainly acute. In a match with some shockingly bad calls, Sharapova's challenges were, with one exception, spot-on, leading Zahlavova Strycova to suggest playfully at one point that the Hawk-Eye system was on the Russian's side.

The second set followed serve until the Russian broke in the deuce-laden sixth game. Sharapova then held in another long game, winning it with a driving forehand at the net. But Zahlavova Strycova was not about to hand the match to Sharapova and took her next service game to love. However, the Russian raised her level, won her own service to love and took the match with a thundering ace down the middle to win 7-5 6-3.

Serena Williams, whom Sharapova beat in the 2004 final, had an easier passage to the last 16. The American started her third consecutive match with a 6-0 first set, this time against Dominika Cibulkova, which she won in just 18 minutes. The diminutive Slovakian, ranked 46 in the world, appeared nervous in her first meeting on any surface with Williams and as if she was on her way to the ignominy of a "double bagel" defeat on Centre Court.

But in the second set Cibulkova settled, held her serve and showed she has some glorious passing shots and topspin ground strokes. But she looked unlikely to get the break as Williams's serve was never going to let her down: Williams rifled 19 aces in the match, which she eventually won in little over an hour, 6-0 7-5. She said afterwards: "Serving that well feels awesome. I serve well at Wimbledon for some unknown reason – I wish I could serve like this every tournament."

Williams and Sharapova, seeded 16 here, have not met on grass since the 2004 final and Williams said of her next opponent: "It's really good to see a champion back on court. It should be a good match. I think she really knows my game, and I pretty much know hers. So I don't think much has changed since then."

Sharapova said of the prospect of a rematch after six years: "It's tough to take anything from that match as it was many years ago. When you step out on court, you start from scratch. The score is 0-0."

On paper, Agnieszka Radwanska's 6-3 6-1 win over Sara Errani of Italy, seeded No 32, looks easy, but it was a closely fought match taking one hour 39 minutes to complete, and involved several rallies with dashing winners both from the baseline and at the net. The Polish seventh seed now faces Li Na , the No 9 seed from China, who had a straightforward 6-1 6-3 win over the Australian Anastasia Rodionova, who had dispatched Svetlana Kuznetsova in the previous round.

On Court 18, the unseeded Czech Petra Kvitova swept past the out of sorts 14th seed, Victoria Azarenka of Belarus, 7-5 6-0, who lost in the final at Eastbourne last weekend apparently carrying a knee injury. Kvitova, a left-hander who had never won on grass before her first match here, now faces the third seed, Caroline Wozniacki of Denmark, who beat the Russian 29th seed Anastasia Pavlyuchenkova 7-5 6-4 and has yet to drop a set at this tournament.

Out on Court 12, two unseeded players had surprise wins. First the Czech Klara Zakopalova beat the 10th seed, Flavia Pennetta of Italy, 6-2 6-3 in a scrappy, error-strewn match, then the Estonian Kaia Kanepi rushed to a 6-1 6-2 defeat of Alexandra Dulgheru, the Romanian 31st seed, in just under an hour.