Samantha Stosur has kept alive her dream of adding a French Open title to her collection by seeing off Bulgaria's Tsvetana Pironkova in a gruelling quarter-final.

With the clouds closing in on Roland Garros, Stosur survived a tense tiebreak to prevail 6-4 7-6 (8-6) in a little under two hours and advance to the final four for the fourth time - adding to a 2010 defeat in the final and semi-final exits in 2009 and 2012.

"I think typically whoever wins a grand slam, they don't always play their best tennis every single day, but they find a way to win," said Stosur, who will rise to at least 14 in the world following the win.