Maria Sharapova was able to celebrate a landmark day as she reached her first French Open final and ensured she will become world number one for the first time in four years.

It has been a long road back for the Russian since shoulder surgery in 2008 that put her out of the game for almost 12 months but she has been in superb form this year and today beat Petra Kvitova 6-3 6-3 in the semi-finals at Roland Garros.

On Saturday she will hope to complete her set of grand slam titles following her wins at Wimbledon in 2004, the US Open in 2006 and the Australian Open in 2008.

And Sharapova will certainly be a big favourite against surprise finalist Sara Errani, who beat US Open champion Sam Stosur 7-5 1-6 6-3 earlier.

The 25-year-old said: "It's just amazing to be back in this position of being world number one again (overtaking Victoria Azarenka).

"I was in a position a few years ago where I didn't quite know if I would ever be here again on this stage playing professionally. And not just at that, but at a level to get to number one in the world and a first Roland Garros final for me. So it's a very special day."

The match was a repeat of last year's Wimbledon final, which Kvitova won, but Sharapova was undoubtedly the better player and showed impressive consistency in very windy conditions.

Her serve has been the major reason she has not managed to win a grand slam title for four and a half years but it was rock solid here and she closed out the match with a second-serve ace.

Sharapova said: "It was tough to play a great match because of the conditions. I think most importantly it was about playing a solid match. I think patience was very important today.

"I was also facing a tough opponent who's given me a lot of trouble in the past. So I was really happy that I was able to win in two sets today."

Kvitova, who also lost to Sharapova in the semi-finals of the Australian Open, was able to reflect on a positive tournament despite falling just short again.

The Czech said: "I wasn't playing bad, but she was better on the court. She deserved it and she's number one now. It's good I can be in the semi-final but next I have to be in a different half than Maria."

Errani's success means there will be an Italian in the women's final for the third year in a row after Francesca Schiavone's two runs, including victory over Stosur in 2010.

But the 25-year-old is an even more unlikely finalist - indeed, she had won only one match at Roland Garros prior to this year and had never beaten a top-10 player.

She broke that duck in the quarter-finals against Angelique Kerber and followed it up with a hugely impressive performance today in a match delayed for more than an hour by rain.

It looked like Stosur had turned things round when she won the first five games of the second set and then clawed her way back from 3-0 down in the decider, but Errani did not waver and served out the win to love.

The Italian, who is also in the women's doubles final, let the emotion show as she sobbed into her towel at the end of the match, and she said of the final moments: "I was very nervous but at the same time I was really focused on the game.

"Maybe she had more pressure. I just wanted to think about what I had to do and try to forget everything, forget where I was."

Errani, who is less than 5ft 5in tall, is having the best season of her career - helped by the change to a longer racquet - and today's win means she will climb into the top 10 from her current ranking of 24th.

She said of her run: "It's incredible for me. I didn't expect it, and I'm here. So I don't know what to say. I'm very happy about how I've played. It's not finished, I have one match more. I have to think about that.

"I don't feel like I'm top 10 but now I will be, so it's a strange sensation. Maybe my problem always was that I couldn't believe that I could beat the strong players.

"But now I beat three in a row. I'm in the final of a grand slam. So I have to maybe try to think a bit different."

It was particularly disappointing for Stosur given she appeared to have conquered her mental weaknesses with last year's brilliant US Open final victory over Serena Williams.

The 28-year-old said: "It just sucks that it happened here today. You do it somewhere else, you don't maybe worry about it so much, but here it obviously hurts a lot more."