Mirra Andreeva defeated 14th-ranked Beatriz Haddad Maia of Brazil 7-6(6), 6-3 to advance to the third round on Thursday.

One day earlier, the 15-year-old Russian upset 2021 U.S. Open finalist Leylah Fernandez of Canada for her first tour-level win.

"Yes, I'm a bit surprised but also everyone was telling me they are playing the same level as you, they are just more consistent," said Andreeva.

"Their mental level is different, but the game-level is almost the same," she added.

With her win over Fernandez, Andreeva became the third-youngest player to win a main-draw match at a Women's Tennis Association (WTA) 1000 tournament, behind American players Coco Gauff and CiCi Bellis, and only the second 15-year-old to defeat a top-50 opponent at a WTA 1000 tournament.

With her victory on Thursday, Andreeva became the seventh-youngest player since 2000 to defeat a top-20 opponent before the age of 16. The Russian’s birthday is on Saturday.

She has won 15 straight matches in all levels and earlier this year became the first player to win two or more W60 titles before the age of 16.

The teenager looked calm and in control throughout the match against the 13th-seeded Haddad Maia. She saved three set points before winning the first-set tiebreaker and then, broke early in the second to secure another straight-set victory.

The WTA Insider asked Andreeva five questions about her career.

Why did you choose tennis?

"Actually, I didn't pick this sport. My mom did. I'm really happy that she did that because honestly, when my coaches give me five days to rest, I cannot even think [about] anything else [but] tennis. I'm really happy that my mom picked this sport because I feel that I really belong to this sport."

What does your first WTA win mean to you?

"After I had the two great weeks in Switzerland and I have a pretty good confidence, so this gives me just much more confidence."

Are you still planning to play junior events?

"I'm limited in tournaments [because of the WTA Age Eligibility Rule]. So I will continue, I think, this year to play some big junior tournaments, maybe Slams."

What is your favorite shot?

"We've been working on my forehand a lot. But for now, I can say that my backhand is my biggest weapon, especially the backhand down the line. Maybe after this, I'll pick my serve because today I did four or five aces.

"Here in Madrid, my serve is really good, so I hope it will be like this the whole tournament."

What has it been like to be at your first WTA 1000?

"I feel a bit weird because it's my second WTA tournament and my first was in Monastir, but there were not a lot of famous players. Here almost every day I see Andy Murray, Daniil Medvedev and all the players from home. They say hi to me and I'm like, 'Wow, how come they know me?' So, yes, it's pretty great."

(With input from AP)