Samantha Stosur overcame a tough early battle and a rain delay to beat unseeded local Kristina Mladenovic and reach the third round of the French Open.

While Stosur’s opening-round victory over Kimiko Date-Krumm was effectively a stroll on the clay for the Australian world No.9, she had to dig a litter deeper in Thursday’s match on Court Philippe Chatrier.

But ultimately she was much too strong in posting a 6-4 6-3 win to set up a third-round clash with Jelena Jankovic.

The match began under threatening skies in the French capital and Stosur took some time to get warm in cool conditions.

She framed a few shots early and Mladenovic proved a stubborn opponent with games on serve until the Australian clinched the first break of serve when up 5-4.

Having squandered three set points, Stosur brought up another with a Hail Mary volley from close range that just caught the line and Mladenovic double faulted to surrender the set.

The second set was more lop-sided and Stosur was coasting towards victory before the rain arrived to halt her momentum when she had just taken a 4-1 lead.

The players returned to court an hour-and-a-half later and there were a few nervous moments as Mladenovic tried to fight back, but Stosur held serve twice to secure the win.

The 29-year-old, a semi-finalist at Roland Garros last year, is optimistic at going deep into the draw in Paris despite a frustrating year marred by injury and form concerns.

She faces a tricky third round opponent in 18th-seeded Serbian Jankovic, who wrapped up a 6-3 6-0 win over Spaniard Garbine Muguruza before the rain hit on Thursday morning.