Faced with the only opponent who has beaten her since February, No.1 seed Ashleigh Barty reversed the result and scoreline exactly, defeating wildcard Paula Badosa 6-4, 6-3 in the Mutua Madrid Open semifinals.

The result extends Barty's red clay winning streak to 16 and puts her into her fourth final of 2021. The Australian has picked up titles at the Yarra Valley Classic, Miami and Stuttgart this season already, and her win-loss record is 25-3.

Barty, who described herself as counting the days until the grass season shortly before winning her first Grand Slam at Roland Garros 2019, hasn't necessarily changed that outlook.

"I've learnt a lot more about [clay], without a doubt," she said. "I promise you, I'm still counting down to the grass court season. It's one of my favorite times of the year. I think the memories and the learnings now that we're getting from the red clay has been really cool, to be able to challenge myself in different ways."

Since leaving home for the first time since the Covid-19 pandemic hit, Barty has only lost once - a 6-4, 6-3 defeat at the hands of Badosa in the Charleston quarterfinals. Her revenge was clinical as she found 30 winners to 23 unforced errors, sealing victory on her second match point with a sixth ace of the day.

"You have to learn from every game, every match you play against an opponent," said Barty. "I definitely learnt a lot from the match we played in Charleston. There was a small adjustment. I think just learning from some of her patterns, tendencies that came through and showed through in that match in Charleston.

"I think I was just able to control the court a little bit better. I was able to look after my service games a little bit better, build pressure on return games. That's a massive part of it: not always winning points, but building pressure. Scoreboard pressure can be a big thing. That was a focus for me today."

Barty reaches first Madrid final with Badosa revenge: Highlights

World No.62 Badosa, the first Spanish player to reach the last four in Madrid in tournament history, is guaranteed to break the Top 50 for the first time next week, and played at a high level in a tight first set. Anticipating Barty's patterns and patiently attacking her backhand, Badosa stuck with her through the first nine games.

But serving to stay in the set, a brilliant Barty lob and a handful of loose Badosa forehands opened the door. Bold winners from Badosa saved two set points, but a double fault on the third was an unfortunate way to finish the opening act.

Badosa battled valiantly to halt Barty's momentum at the start of the second set. But after an early exchange of breaks, another double fault from the home player put Barty up 3-1. The World No.1 survived three break-back points in the next game to consolidate for 4-1, holding with an exquisite dropshot.

"It was important for me to get that early break back in the second and keep my nose in front, almost force her to come up with something that was going to be at a really, really high level to be able to get back into the match," said Barty.

That tussle proved crucial as Barty conceded just two more points on serve to seal her place in a first Madrid final against either No.5 seed Aryna Sabalenka or Anastasia Pavlyuchenkova.