Paris: Samantha Stosur has stormed into the second week of the French Open with a straight sets third-round dispatch of American qualifier Bethanie Mattek-Sands.

Australia's lone survivor in the singles draw blew Mattek-Sands off the court 6-2 6-2 in barely an hour to set up a last-16 meeting on Sunday with Latvian Jelena Ostapenko.

A quarter-final against former champion Svetlana Kuznetsova or Caroline Wozniacki looks imminent as Stosur showcased her title credentials with four aces, seven service breaks and some of the fastest deliveries of the championships.

Yet to drop a set all tournament, the victory in her milestone 50th match at Roland Garros was Stosur's eighth in a row on European clay and thrust the 33-year-old into the business week in Paris for the sixth time.

Mattek-Sands trudged onto Court 3 with her left thigh heavily strapped and proceeded to make a horrible start.

The six-times grand slam doubles champion was flabbergasted when foot-faulted on the second point of the match.

"No way," Mattek-Sands repeatedly protested to the chair umpire. "I never foot fault."

Rattled, she dropped her opening two service games as Stosur steamed to a 3-0 lead for the loss of only three points.

Mattek-Sands finally got on the board in the fourth game but Stosur broke straight back before clinching the first set in 31 minutes.

The pair traded early breaks in the second set as Australia's former finalist at Roland Garros sloppily dropped serve from 40-15 up in the fourth game.

But as hovering storm clouds threatened to stall Stosur's progression, the 23rd seed wrestled back control with some piercing backhand return passes and her trademark forehand power.

Violent thunder almost forced the pair off court with Stosur five points from victory.

But after consulting officials, the umpire allowed the combatants to play on, with Stosur wrapping up the match in one hour and 10 minutes.

AAP