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The Ukrainian, whose only previous triumphs came in Austin in 2023 and Rouen last month, arrived in the Spanish capital on a mission and left with silverware after a display brimming with intent and nerve.

Kostyuk began with relentless intensity, stepping into the court and striking as if every blow might be the last. She brought raw power and will, while Andreeva countered with a more polished, patient approach, mixing up her shots in a way that at times frustrated her opponent.

But it was Kostyuk who seized control. In the sixth game of the opening set she piled on the pressure, drawing a string of unforced errors from the Russian before breaking for a 4-2 lead. Another commanding hold stretched her advantage to 5-2.

Serving for the set, however, Kostyuk wobbled.

She offered up two break points, which she saved to reach deuce, only to double fault on set point and level the contest once more. Regaining her composure, she closed it out 6-3 after 34 minutes.

"It feels unbelievable to be standing here right now," Kostyuk said.

" I can only thank my team for supporting me throughout the years. If you look at the stats, I was way down the line and never thought I would be standing here where I am right now, playing the way I'm playing."

Andreeva, who turned 19 this week and is No.8 in the world rankings, has long been regarded as one of the game's most gifted young players.

Yet in Madrid she again seemed to be struggling when cast in the role of favourite.

The second set swung wildly. Andreeva donated an early break with successive unforced errors, then immediately hit back, earning two break points after a Kostyuk double fault and levelling at 1-1.

She surged to 3-1 when Kostyuk missed a routine smash, the Ukrainian staring in disbelief as momentum appeared to shift.

It did not last. Kostyuk struck back for 3-3, capitalising on triple break point, and the match turned into a test of nerve.

Leading 5-4 with Kostyuk serving to stay in the match, Andreeva conjured up three superb rallies to reach deuce but squandered a set point with an unforced error.

She earned another with a dazzling winner, only for Kostyuk to hammer down two successive aces and level at 5-5.

The Russian's rollercoaster afternoon ended with a double fault that gave Kostyuk the decisive break at 6-5.

This time there was no hesitation. Kostyuk served out the match in commanding fashion to secure a title that underlined both her firepower and resilience.

The 23-year-old Ukrainian posed for photographs at the Caja Magica later, and it was not just the silverware that caught the eye.

Held alongside her team and her two dogs, Kostyuk showed off a piece of men's underwear, prompting raised eyebrows and plenty of laughter.

"We have a tournament laundry service and sometimes the clothes get mixed up and last year we ended up with this piece of underwear where in it was written 'Lucky Shorts'. So we kept it," Kostyuk said.

"My coach Sandra [Zaniewska] kept it as a lucky charm.

"She drove to her father's house just to pick it up before traveling here again for the tournament. And we made this promise that if I'd win we would bring the 'Lucky Shorts' for the photoshoot with the trophy."