MADRID, Spain - No.6 seed Karolina Pliskova ended No.1 seed Simona Halep's dreams of a third consecutive Mutua Madrid Open title in the quarterfinals, putting on a stellar 6-4, 6-3 performance to move into the final four for the first time.

The result ends the Romanian's winning streak in the Spanish capital at 15, but extends Stüttgart champion Pliskova's own current run to nine - tying her second-longest streak, set in January 2017 across Brisbane and the Australian Open.

Read more: Pliskova: 'I think I played one of my best matches on clay in my life'

Following Pliskova's third-round defeat of Sloane Stephens, an opponent she had never previously beaten, the Czech said that her aim against Halep would be to play "controlled aggression" in a bid to overturn a 1-6 head-to-head.

This she did to perfection. As in the Stephens match, the 2016 US Open runner-up was slower out of the blocks, out-manoeuvred by her opponent and broken the first time she stepped up to the line to fall behind 0-2. At this point, the pattern looked much like Halep's six previous wins, across which Pliskova had won only one set.

However - in another echo of her third-round win - last year's Roland Garros semifinalist responded by roaring back with impenetrable serving and a dominant ground game.

Patiently absorbing Halep's groundstrokes, Pliskova would utilize greater topspin to rally safely with one of the game's greatest counterpunchers before choosing the right moment to unleash her full power - resulting in a ratio of 20 winners to 16 unforced errors. 

As the match progressed, it would frequently be the two-time Roland Garros finalist whose groundstrokes would break down first in longer rallies, and she would rack up 26 unforced errors as she found herself in the unusual position of being unable to find a way through Pliskova.

The former World No.1's new strategy didn't come at the expense of her basic strengths, though, and she maintained the superb level of serving that has been on display all week. A 70% first serve percentage had led the way to a win over Victoria Azarenka in the second round, and Pliskova raised that number to 78% to overcome Stephens - and today, a 70% figure helped ensure that, following that initial break, she would not face another break point in the match. 

Indeed, from 0-2 down the Australian Open quarterfinalist would lose only one more point behind her serve in the first set, sealing it with three consecutive love holds.

Despite three double faults - one in the final game of the match as she was broken to love - Halep did not serve badly herself, also maintaining a 70% first serve percentage. Pliskova, however, had a firm handle on it, frequently stepping into the court to smack away disdainful return winners. 

This particularly occurred at crucial stages of the match: converting a break point to move up 4-3 in the first set; twice as Halep served to stay in that set; on the first point as Halep served to stay in the match. If Pliskova's macro strategy was one of controlled aggression, this instinct for upping the pace at the right moment was also an example of how it also applied at a micro, point-to-point level - and exemplified the absolute clarity with which she was executing her game today.

Now the highest-ranked player remaining in the draw, Pliskova's reward in her maiden Madrid semifinal will be an encounter with either No.10 seed Petra Kvitova or No.14 seed Daria Kasatkina for a chance to make her first ever Premier Mandatory final.