MADRID -- Number 1 seed Ashleigh Barty booked her place in the women's singles final in the Mutua Madrid Open on Thursday with a straight-set 6-4, 6-3 win over Spanish wildcard Paula Badosa.

The win extends Barty's winning run on clay to 16 matches and also avenged the defeat she suffered to Badosa in Charleston in April. Indeed, Badosa, who is the first Spanish woman to reach the semi-finals in Madrid, is the only player to have beaten the Australian since February.

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

Badosa, ranked 62nd in the world, matched Barty shot for shot in the first set, only to lose her serve in the 10th game, she saved two set points, but then double-faulted on the third.

Another double fault allowed the Australian to go 3-1 up in the second set and although Badosa looked to react and forced three break points in the next game, Barty saved them all to move 4-1 up, from which point she closed out the match.

Barty will now face No 5 seed Aryna Sabalenka of Belarus who defeated Russian Anastasia Pavlyuchenkova 6-2, 6-3 in the other semifinal.

In the men's tournament, No 1 seed, Rafael Nadal kept on track for a sixth Madrid title with a 6-3, 6-3 win over Alexei Popyrin.

"It was difficult. The court today was slippery, it was very fast, very dry conditions. The ball was flying a lot. The beginning of the match was super tough. Every match is difficult," said Nadal, who has reached the quarter-finals in the tournament every year since 2012.

Second seed Daniil Medvedev won't be in the last eight, however, after he once again struggled on clay and crashed out 6-4, 6-7(2), 6-1 to Cristian Garin, who served exceptionally well and faced just one break point all match.

Two-time runner-up Dominic Thiem advanced to the quarter-finals with a 7-6(7), 6-4 win against Alex de Minaur in which he saved a set point in the first set tiebreak.

Thiem will face big-serving John Isner for a place in the quarter-finals after the American won a tight three-set match 7-6 (4), 3-6, 7-6 (4) against the recent runner-up in Monte-Carlo, Andrey Rublev.

World ranked No.44, Alexander Bublik also made it into the last eight thanks to a 6-4, 6-3 victory against Aslan Karatsev.