PARIS, France - No.1 seed Simona Halep roared back to overcome No.12 seed Angelique Kerber 6-7(2), 6-3, 6-2 to book her place in a third Roland Garros semifinal, emerging on top of a magnificent contest decided by the narrowest margins.

No quarter was given over the first two sets of this quarterfinal, with both players using every inch of court to try to out-manoeuvre each other and, whenever momentum seemed to be with their rival, managing to come up with brilliant shots to reel the lead back.

The World No.1 was slower out of the blocks, though, committing seven unforced errors in the first two games to fall a break down immediately. Kerber, spreading her groundstrokes around the court with immaculate depth and redirection, was able to hold Halep off even after the Romanian began to get her teeth into the rallies, emerging out of two tight multi-deuce tussles to extend her lead to 4-0.

But the two-time Roland Garros runner-up was in no mood to let the set go. From that point, Halep pushed herself to become increasingly aggressive, and it was her groundstrokes that probed more angles and lines as she tried to open up the court.

The strategy was a double-edged sword. Striking her forehand with real ferocity, Halep retrieved one of the breaks with a drive volley winner - and Kerber, playing more conservatively, failed to regain her lead in the next game after some untimely forehand errors. Dictating off the ground and playing some of the best volleys in her career, Halep would prevent the German from serving the set out to level the score at 5-5.

But the 26-year-old, playing with lower percentages than she often does, ultimately landed just 14 winners to 30 unforced errors in the first set - and six of the latter came, with unfortunate timing, in the deciding tiebreak.

Nonetheless, Halep's overall level of play had been in the ascendancy for most of that set's second half - and, continuing to take control from the baseline, she immediately took her first lead of the match with a break in the second set. Though Kerber, sensing a pendulum swing, cut her passive play out and began to construct her most aggressive points of the match, Halep would be able to protect that advantage throughout the set. 

Now winning 85% of her first serve points compared to just 47% in the first set, the Rome finalist faced just one break point across the second stanza - saved when Kerber leaked another backhand error, before Halep held with a brilliant counterdrop.

With her intensity dipping again, two double faults in the subsequent game from the 30-year-old - one down set point - conceded the set. And once more, it was Halep who came out on fire for the decider, upping the pace on her groundstrokes and coming to net to finish points off with alacrity.

Though Kerber continued to cling on to the match, coming up with a delightful dropshot-volley combination en route to breaking back, Halep's ability to carve up the court with sharp angles and laser-like line shots was in full flow now. Following a medical time-out that the Sydney champion took for her foot, Halep would accelerate towards the finishing line by capturing four of the final five games; suffocating on attack and impenetrable on defence, the World No.1 was both irresistible force and immovable object.

That honor will be on the line tomorrow against semifinal opponent Garbiñe Muguruza: whichever player wins that match, their first encounter since the Spaniard won 6-1, 6-0 in last year's Cincinnati final, will come out of Roland Garros as the No.1.

Read more: As it happened: Halep outlasts Kerber to book Muguruza clash