Tennis-obsessed Eugenie Bouchard was in grade school when she first met Maria Sharapova and summoned her courage, at a tournament in Miami, to ask for a photograph together.

When they met Thursday at Roland Garros with a spot in the French Open final at stake, the 20-year-old Bouchard dispensed with awe and set about remorselessly pummeling her childhood idol to claim the opening set on Court Philippe Chatrier.

But on a day when her serve gave her fits, Sharapova, 27, asserted her mettle to storm back for a 4-6, 7-5, 6-2 victory that proved yet again that the Russian’s biggest weapon is her iron will.

“I fought, I scrambled and I found a way to win,” said Sharapova, who will seek her fifth major title Saturday, having completed a career Grand Slam in 2012 on the same Parisian red-clay court.

It will mark her third consecutive French Open final, pitting her against fourth-seeded Simona Halep of Romania, who dismissed Germany’s Andrea Petkovic, 6-2, 7-6 (7-4), in Thursday’s other semifinal.

Canada's Eugenie Bouchard returns the ball during the semifinal match. (Michel Euler/Associated Press)

Halep, 22, whose rapid ascent in the rankings has mirrored Bouchard’s, has yet to lose a set in the tournament. But she has never beaten Sharapova in three previous meetings, falling most recently in a clay-court final in Madrid.

“I don’t know,” the 5-foot-6 Romanian said when asked how she planned to solve Sharapova. Halep is smart and quick on court but gives up eight inches in height and six years’ pro experience to Sharapova.

“I know I’m short,” Halep said with a smile, “but I have to be happy and just enjoy.”

Few would have predicted this championship pairing when the 2014 French Open dawned May 25.

But top seed and defending champion Serena Williams, heavily favored to claim the 18th major that would have tied the singles mark shared by Chris Evert and Martina Navratilova, was toppled in the second round. Second-seeded Li Na, the 2011 French champion who started the year by claiming her second major, the Australian Open, failed to win a single match. And third-seeded Agnieszka Radwanksa tumbled in the third round.

Of the four semifinalists, Sharapova was the only one who had reached a Grand Slam final — not to mention won all four (Wimbledon in 2004, the U.S. Open in 2006, the Australian Open in 2008 and the French in 2012).

She also dwarfed the others in star wattage — not simply a former No. 1 with $28 million in career prize money but a global brand with multimillion-dollar endorsement deals with Porsche, Nike and Cole Haan, among others.

Maria Sharapova of Russia returns a shot. (Clive Brunskill/Getty Images)

Sharapova strode onto Philippe Chatrier court trailed by a 20-year-old who looked, at first blush, like a slightly smaller version of herself.

Like Sharapova, the 5-10 Bouchard wore her long, blonde hair in a ponytail secured by a visor. Outfitted by Nike as well, Bouchard sported a flouncy tangerine dress nearly as coquettish as Sharapova’s pink and orange frock.

But the pretty dresses were mere sugarcoating on two gritty brawlers who make no apology for caring more about winning matches than making locker-room friends. They are fierce competitors.

Bouchard had failed to win a set against Sharapova in their two previous meetings, both last season. Since then, the Canadian had climbed from 67th in the world to 16th with an aggressive baseline game that’s predicated on attacking the ball on the rise.

It carried Bouchard to the semifinals of this year’s Australian Open, so she felt entirely deserving of her place among the French final four. She broke Sharapova in the third game of the match. And after Sharapova broke back, Bouchard broke again to claim the first set.

Both played a ragged, scrappy second set that Sharapova closed, following a rash of service breaks, by capitalizing on one too many forehand errors by Bouchard.

With a game that’s best suited to hard courts, Sharapova once described herself as “a cow on ice” when competing on clay. In many respects, being 6-2 is an asset in women’s tennis, but it doesn’t lend itself to fleet-footed movement on clay. Still, the Russian has developed a flair for sliding on the surface, and it helped her defend better in the third set.

Sharapova also drove the ball deeper and solved the yips in her serve in the decisive set, never facing a break point while twice breaking Bouchard.

“At the end of the day, it’s not how you finish the first set,” said Sharapova, now 53-4 on clay since 2012. “It’s how you finish the last set.”

Halep confessed she struggled to control her emotions when she stepped on court for her first Grand Slam semifinal. But after a few shots, she settled into her game, firing sharply angled groundstrokes and mixing in tricky drop shots to trip up Petkovic.

Ranked 45th in the world one year ago, Halep will rise to No. 3 when the rankings are computed Monday.

“I had impressive 12 months,” she conceded, “but today at this tournament — it’s fantastic. Now I have emotions also to speak and to say how I feel. It’s incredible.”