Romanian Simona Halep showed the full extent of her defensive skills to beat Karolina Pliskova 6-4, 3-6, 6-3 and reach her second French Open final in Paris on Thursday.
The third seed, who will become world number one if she defeats Latvia's Jelena Ostapenko in Saturday's showdown, benefited from her opponent's unforced errors in the first set before Pliskova rediscovered her touch.
Overwhelmed by Pliskova's power in the second set, Halep regained the momentum in the decider, frustrating her second-seeded opponent with her ability to soak up punishment.
She ended the contest on her first match point with an unreturnable serve to reach her second Roland Garros final after losing the first one to Maria Sharapova in 2014.
Ripping a screaming forehand straight through the tennis textbook, Latvian Jelena Ostapenko blazed into the French Open final with a 7-6(4), 3-6, 6-3 win over Swiss Timea Bacsinszky in a battle of the birthday girls.
On the day she turned 20 the free-swinging world number 47 launched a fusillade of 50 winners to become the first unseeded player to reach the women's singles final at Roland Garros since Mima Jausovec lost to Chris Evert in 1983.
But seven-times French Open champion Evert, in Paris commentating for broadcaster Eurosport, would not have recognised the high-risk tennis served up by Ostapenko who clearly does not subscribe to the old-school theory of waiting for your opponent to make a mistake.
Mixed in with her scintillating winners, including forehands faster than anything men's world number one Andy Murray has managed here so far, were 45 unforced errors, some of which could have embellished a video nasty.
At times it resembled Russian roulette as Ostapenko threw caution to the wind. But there was nothing lucky about the way she prevailed in the biggest match of her career.
"I didn't think I would be in the final but every match I've played better," Ostapenko, whose dad Jevgenijs was a professional football player, told reporters.
"In the third set I just wanted to stay playing aggressive. "It's a great way to celebrate my birthday."
Sixteen service breaks summed up the frantic nature of the contest. Several times Ostapenko seemed on the verge of youthful tantrum in the hot Court Philippe Chatrier sunshine, especially when the Latvian livewire lost four games in a row to lose the second set -- ending it with a double-fault.
Thirtieth seed Bacsinszky, who needed a bandage applied to her right thigh midway through the first set, looked the more likely winner at that point as she sought to celebrate her 28th birthday by surpassing her semi-final run of 2015.
Logic suggested the steady approach she adopted after losing a topsy-turvy first set in a tiebreak would get the job done for the experienced Swiss, not the white-knuckle rollercoaster tennis Ostapenko was playing.
