Along with another dose of Roland Garros regrets, Samantha Stosur will leave the French Open with renewed belief she’s not yet a spent grand slam force.

Australia’s top-ranked tennis player was left to rue another one that got away in Paris as she squandered a one-set lead against tournament favourite Maria Sharapova in the fourth round on Sunday.

The 3-6 6-4 6-0 loss was particularly hard to swallow given the women’s draw had opened up like never before, with the top three women’s seeds failing to reach the last 16.

No.19 Stosur defied expectations just to give the seventh-seeded Russian a significant scare.

But the fact she not only matched it with the 2012 champion, but dominated her for large periods before being blown away in the final set, made it all the more painful.

“I know it was an opportunity lost,” Stosur said.

“I thought I was there to win that match and definitely playing well enough to do so.

“I know that’s an opportunity I’m not going to get again.”

A three-time semi-finalist at Roland Garros, and runner-up in 2010, many view the French Open as Stosur’s best opportunity to add to her 2011 US Open triumph.

At 30, the clock may be ticking on that quest but her run at Roland Garros this week has offered a timely boost just as many feared her career may be in decline.

Struggling for consistency and with her ranking dropping steadily, Stosur had not been past the third round at a major since her US Open title defence in 2012.

“I played well here. Probably some of the best tennis I have played for quite a few months,” Stosur said.

“It’s something that I’m definitely very happy about. Something that I’m going to build on.

“But I also know that this week was a week where maybe I could have done a bit better.”

Stosur admitted her showing in Paris had helped restore some confidence that had been lacking in recent months.

She said it also reinforced the need to stick with the positive, aggressive approach that has worked so well in the past.

“I’ve got to take my game to my opponents,” Stosur said.

“I think that’s definitely something I have done for probably 95 per cent of the time this week.”

Stosur will now turn her attention to the grass and while it’s typically the surface she’s struggled most on, she is optimistic after matching her best effort at Wimbledon by reaching the third round last year.

It will also be her first foray on the grass under the tutelage of Brit Miles Maclagan, former coach of Wimbledon champion Andy Murray.

“(Last year) has got to be something that I can keep in the front of my mind and think, ‘OK, I’m feeling a lot more comfortable on this surface’,” said Stosur, who will play in the Wimbledon lead-up event at Eastbourne.

“It’s going to be a tough few weeks. It’s always rough until you find your rhythm and your footing and everything else.

“But I think it’s a time where I’m feeling good with the way that I’m playing again so it’s a matter of trying to build on that.”

Stosur’s performance in Paris again masked another largely underwhelming performance for Australia in singles at Roland Garros.

Of the nine-strong Australian contingent only Marinko Matosevic and Casey Dellacqua joined Stosur in making the second round.