"I think one of them got a wildcard in the main draw, " Sharapova said.

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The 16-year-old had been given a wildcard into the main draw after rising to 234 in the world rankings.

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However, last year's runner-up Ryan Day cannot qualify for the semi-finals after a surprise 3-3 draw with Maltese wildcard Alex Borg .

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On the same side of the draw, Zvonareva is next up against unseeded Belgian Yanina Wickmayer, who beat American wildcard Jill Craybas 7-6 (7-2) 6-1.

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