WHAT a difference a day makes.

When rain stopped play here on Tuesday, a hapless Maria Sharapova had lost the first four games of her quarter-final encounter against Marion Bartoli of France, a disadvantage which was unable to prevent the Russian No.3 seed dropping the first set when they resumed yesterday. But, despite enduring severe difficulties on her ball toss throughout this quarter final, the 25-year-old found an extra edge from somewhere to complete a 3-6, 6-3, 6-4 win in two hours 32 minutes to move into the semi-finals at the US Open for the first time since her victory here in 2006. Fittingly, considering her battle with her serve, the victory was delivered with an ace. Sharapova deserved the plaudits for putting herself out there but for the second match in a row she gave thanks to the intervention of the elements. That is despite the intermittent rain in Queens yesterday morning meaning that on no fewer than four occasions the players were prepared to go on court, only to be hauled off again at the last moment. "We were literally in the hall of the locker room then went back off because it started drizzling," she said. "I must have done 20 different types of warm-up in the gym. I was like 'let's just play tennis'.

"But I think the rain break gave me a few hours to think about things. I got a good night's sleep first of all. It was an 11am start and I knew the match wasn't over and I still had a chance. I had just had a bad four games. It is about who wins the last point. I am so happy to get through this one and so happy to be back to this stage at the US Open."

The French Open champion faces Victoria Azarenka of Belarus in the semi-final, dreaming of revenge for a defeat at this stage in the Australian Open earlier this year. "She beat me in Australia and I would love to get my revenge," Sharapova said. "It's always tough to lose in that stage of a Grand Slam. I think many people expected her to win a Grand Slam earlier than she did. She always had a solid game but she was always a little mentally fragile."

The same can no longer be said about Sharapova. This victory means that, of the 12 matches she has played this year which have gone to three sets, she has won them all.

"It shows that I enjoy the battle no matter what the score is," she said.

Joining the Russian in the last four is Sara Errani, the Italian who she beat to claim her career slam at Roland Garros earlier in the year. The 25-year-old from Bologna faced her doubles partner and countrywoman Roberta Vinci in the quarter-finals.

Vinci had no answer to the world No.9 and detained her for just one hour 12 minutes en route to her 6-2, 6-4 victory. "A quarter-final against your best friend is difficult," said Errani, also the world No.1 doubles player. "There is much tension. Normally when we walk on court, we go together and speak. Today was strange but sometimes it happens."