It’s not often that a preteen player wants to make a fundamental, technical change to her game. But that’s exactly what Austria’s Lilli Tagger wanted to do at 10 years old.

Tagger played with a two-handed backhand but — inspired by Roger Federer and compatriot Dominic Thiem — wanted to switch to a one-handed backhand. It took two years — and winning a bet with her coach — before she was allowed to do it.

“Actually that was my own decision,” the 17-year-old told wtatennis.com in Mumbai about the switch. “I wanted to switch it when I was 10 but everybody told me ‘No, you shouldn’t do it, it’s not good for you.’

“Then when I was 12, I had a bet with my coach and I told him ‘OK, let’s do this. If I win the tournament, I will change. Otherwise, I will never ask you again.’ And I went on to actually win the tournament that week.”

Tagger said it took about a year to fully adapt to the one-hander, a shot that is now quite uncommon on the WTA Tour Driven by Mercedes-Benz. Around that same time when she was 13 years old, she moved to train in Italy. There two years later, she started working with 2010 French Open champion Francesca Schiavone, who’s also known for her one-handed backhand.

“I think she knows the game very, very well. She understands me, of course, very well, as well as the one-handed backhand, the game style. She’s very strong there, so she helps me a lot. But I think it’s more the mental part. She has helped me a lot in the last year and I’m super happy to have her,” said Tagger, whose breakthrough on the junior Grand Slam circuit came at Roland Garros last year.

“When I was in Melbourne last year for the Australian Open juniors and we finished it (quarterfinals) I was like ‘Okay, I want to win one of those.’ I thought if I have a chance, it would be on clay. So we set the goal and then we actually won it. It was amazing.” 

While her one-handed backhand may be the first thing that stands out, there is plenty more to like about Tagger’s game. She has a tall frame, a big serve — she hit 33 aces in five matches in Mumbai this week — and a powerful forehand to complement her signature shot.

Those weapons have helped make Tagger one of the most exciting young prospects in women’s tennis. She has surged up the rankings over the past 14 months, rising from outside the top 700 in January 2025 to her current ranking of No. 128 in the PIF WTA Rankings. In that span, she reached her first WTA 250 final in Jiujiang and won four ITF titles, the biggest coming last week at the ITF W100 in Fujairah.

“If you had told me 12 months ago that this is where I would be, I would not believe you,” Tagger said.

At this week’s L&T Mumbai Open WTA 125, Tagger won four matches to reach the final before falling to Thailand’s Mananchaya Sawangkaew 6-4, 6-3 in one hour, 25 minutes.

The loss ended a nine-match winning streak, but her run will see her break into the top 120 on Monday. That moves her closer to her immediate goal: earning direct entry into the French Open women’s singles main draw. Her long-term ambition is even bigger — to become world No. 1 and win multiple Grand Slam titles.

Having grown up in Austria and trained in Italy, it’s no surprise clay is Tagger’s favorite surface, and Roland Garros remains one of her two picks for the Grand Slam she wants to win the most. Her other choice may surprise many.

“I think it would be funny but again Paris. Since I won it first as a junior, and then again to win it on the women’s side. But I think Wimbledon is also very special. So one of those two.”

Tagger has made a habit of surprising herself — and plenty of others — over the past couple of years, and for her, little seems out of bounds.