Volkswacht Bodensee - All grown up: Andreeva 'mentally and physically' stronger at French Open

The 18-year-old, seeded sixth at Roland Garros, earned a 6-3, 7-5 win against Russian-born Kasatkina, the world number 17 who now competes for Australia.

She will next take on 361st-ranked Frenchwoman Lois Boisson who shocked third seed Jessica Pegula of the United States.

"I think I am much stronger than I was two years ago," Andreeva told journalists.

"I think that for me, the most important two points that changed is I improved physically and also mentally.

"I'm much more positive right now on the court, and I think that also is one of the keys for me.

"And yeah, I'm always trying to now fight for every point no matter what happens."

Andreeva came from 5-3 down in the second set and saved one set point on her way to her second Grand Slam quarter-final.

She converted four of seven break points and became the youngest player to reach back-to-back Roland Garros quarter-finals since Martina Hingis in 1997-98.

Andreeva reached the semi-final last year with a shock quarter-final win over Aryna Sabalenka.

She is hoping for another strong performance at Roland Garros, with both Sabalenka and reigning champion Iga Swiatek in the other half of the draw.

"I was prepared for the battle, last time we played each other I lost in three sets and it was a pretty dramatic match," said Andreeva, who suffered a tearful loss to Kasatkina in the Ningbo final last year in China.

"I don't know what changed, but today was not that hard to kind of change my mindset and step on court and... be opponents (with Kasatkina).

"I don't know how, but I managed to kind of tell myself that I'm playing against the ball, not against the opponent.

"It gives me confidence. I'm just happy I closed the match in two sets."

Kasatkina believes world number six Andreeva, who already has three WTA titles to her name, is hitting her stride.

"Honestly, I feel like she's taller and taller every single week," said the 28-year-old.

"I see a lot with the serve that she's improving because of practising a lot, so I see that her serve improving every time.

"Mentally she became stronger as well, but this is something I see every time we are hitting the practice court."

A.Zbinden--VB