(REUTERS) - Serena Williams overcome the gritty challenge of unseeded Dutchwoman Kiki Bertens 7-6(9-7), 6-4 on Friday to reach the French Open final, putting the world No. 1 just one match away from a record-equalling 22nd Grand Slam singles title.

Williams, who won the first of her three Roland Garros crowns in 2002, survived a first-set scare for the second day running, saving two sets points before winning the tiebreak.

With the Philippe Chatrier showcourt still little more than half full as unseasonably cold kept thousands of ticket-holders away, the drama continued into the second set, when Williams was broken again to trail 2-0.

But she broke straight back and conceded just two further games to reach Saturday's final, where she will face Spanish fourth seed Garbine Muguruza hoping to equal Steffi Graf's Grand Slam singles record.

Muguruza defeated Australian Samantha Stosur 6-2, 6-4 to reach her second Grand Slam final.

The 22-year-old, runner-up at Wimbledon last year, became the first Spanish woman to reach the Roland Garros final since Conchita Martinez in 2000.

Muguruza made the most of Stosur's mediocre first serve on Court Suzanne Lenglen to race to a 4-0 lead in the opening set, also relying on her booming forehand to outpace the 2010 runner-up.

Muguruza held off Stosur's late comeback charge to set up a final showdown with Williams.