Sam Stosur celebrates her quarter-final success.
Sam Stosur celebrates her quarter-final success. David Vincent

Sam Stosur into French Open semis

AUSSIE Sam Stosur has defied the weather and a poor run at grand slams to reach her fourth semi-final at the French Open.

Stosur had twice had to play on consecutive days because of the inclement Paris weather but showed her fighting qualities on another damp day to defeat Tsvetana Pironkova from Bulgaria in straight sets, 6-4 7-6.

The 2010 finalist trailed 4-2 in the first set before fighting back to win it and was also down 3-1 in the second before taking the set to a tie-break.

Stosur, seeded 21, was 5-1 down in the tie-break but stormed home on another damp evening on Philippe-Chatrier Court.

The Aussie will play No.4 seed Garbine Muguruza in the semi-final and the 32-year-old said she was glad to have got past Pironkova

"It was really tricky today," she said.

"She has all different sorts of paces. Sometimes she gives you nothing and then she can really hit it.

"It was really tough out there today, so to get through that in straight sets, I'm really happy."

World No.1 Novak Djokovic set up a quarter-final tonight with Tomas Berdych after defeating Spain's Roberto Bautista Agut 3-6 6-4 6-1 7-5 in their rain-delayed match.

Serena Williams is also in action tonight in a last-eight clash with Yulia Putintseva of Kazakhstan after defeating Ukraine's Elina Svitolina 6-1 6-1.