10 terrific teenage transformations

The full version of this feature appears in Australian Tennis Magazine’s April/May issue, which has a special theme of ‘turning points’. Now in its 50th year, Australian Tennis Magazine continues to bring you in-depth coverage from the international tennis circuit plus features, instructional content and more. Visit the online shop to preview and order your copy.

Tennis, it seems, is no longer the exclusive domain of established favourites.

Recent wisdom suggested that as the sport became increasingly physical, and careers extended longer, more battle-hardened were likely to succeed.

That was until a bunch of talented young players burst onto the scene and transformed the tennis landscape.

We celebrate 10 of those teenage breakthroughs, several of which have come this year.

1. Jakub Mensik

It was the ultimate case of the apprentice outclassing the master when Jakub Mensik, at age 19, stunned Novak Djokovic in the final to claim his first career title at the Miami Masters.

Djokovic inspired the teen’s start in the sport and has since trained with the young Czech – perhaps helping instil the resilience that saw Mensik overcome a knee injury that almost forced his withdrawal just hours before the tournament.

“[I’m] never really happy to lose, but [Jakub's] one of the very few players that I would be happier to lose to, to be honest,” said Djokovic, who at age 37 was targeting a milestone 100th career title. “To see his development and evolution is really great.”

After a finals appearance in the AO 2023 boys’ tournament, the 193cm-tall Mensik made rapid gains in his early steps at professional level, stunning Andy Murray, Andrey Rublev and Gael Monfils to reach a first ATP-level final in Doha, aged 18, in 2024.

Top-20 wins over Grigor Dimitrov, Felix Auger-Aliassime and Casper Ruud followed, but it was in Miami in March that Mensik made his biggest statements, outplaying No.6 seed (and newly crowned Indian Wells champion) Jack Draper, No.3 Taylor Fritz and Djokovic.

“It was because of him basically I started to play tennis,” So it just feels incredible that I had the opportunity for a second time to play against him,” said Mensik, who rose to a career-high ranking of No.24.

“To beat him in this tournament in the finals … it was just a dream to win an ATP tournament, and even better that it's [an ATP Masters] 1000. Playing against Novak in the finals makes it more special.

“Right now, it's biggest win of my career so far, and I'm just super happy with that. But I know that this is not the end, and I know that this is just the beginning for me.

“I'm hungry for more.”

2. Mirra Andreeva

Landmark accomplishments are quickly piling up for Mirra Andreeva.

The 17-year-old took down three Grand Slam champions – Marketa Vondrousova, Iga Swiatek and Elena Rybakina – on her way to becoming the youngest champion of a WTA 1000 tournament at Dubai and followed up with the Indian Wells title.

She became the youngest player to crack the top 10 since Nicole Vaidisova in 2007. The bubbly teen followed in famous footsteps in making her top-10 debut before turning 18, joining Martina Hingis (in 1996), Venus Williams (1998), Anna Kournikova (1998), Serena Williams (1999), Maria Sharapova (2004) and Vaidisova (2006).

With Andreeva’s 18th birthday looming late in April, many “youngest since” milestones still beckon.

3. Joao Fonseca

Armed with a forehand that strikes fear into the most accomplished opponents and his self-described “gift of being calm” in any circumstance, Joao Fonseca has set the tennis world abuzz in recent months.

After winning the Next Gen ATP Finals at Jeddah in December – where at age 18, he was the youngest champion of the tournament since Jannik Sinner five years ago – the Brazilian constructed a 14-match winning streak as he won the Canberra Challenger and progressed to the AO 2025 second round as a qualifier.

His victims in Melbourne included No.9 seed Rublev. Fonseca maintained momentum to lift his first ATP-level trophy in Buenos Aires, joining names including Lleyton Hewitt, Kei Nishikori, Rafael Nadal and Carlos Alcaraz as the 10th-youngest champion in ATP history.

4. Shang Juncheng

Shang Juncheng, fondly known as Jerry, made history when he became the first Chinese teen to enter the ATP’s top 100 in May 2024.

The then-19-year-old achieved another accolade as he claimed a first singles title in Chengdu last September.

“It’s always special to play at home, not mentioning to win a title,” said Shang, who beat stars including Kei Nishikori and Lorenzo Musetti to become only the second Chinese man (alongside Dallas 2023 champion Wu Yibing) to win an ATP title.

“I never thought that I would do it this early in my career.”

5. Coco Gauff

When American favourite Coco Gauff celebrated her milestone 21st birthday in March, you could reasonably argue she’d already come of age.

Gauff was just 15 when she won her first career title at Linz, Austria in 2019 and was a five-time WTA champion before her crowning achievement at the 2023 US Open, when the then-19-year-old beat Aryna Sabalenka in the final.

Proving herself a wise head on young shoulders in that come-from-behind victory, Gauff also showed she could manage the pressure of expectation.

“I feel like this is a big achievement, but honestly, I feel like I’ve been so used to this since I was basically 15 years old,” Gauff smiled. “I still am hungry for more but I’m just going to enjoy this and not look too far into the future.”

6. Arthur Fils

While often referenced alongside Giovanni Mpetshi Perricard and Luca Van Assche as the future of French tennis, Arthur Fils is the only member of that group to win an ATP title as a teen.

Fils claimed the first of three career titles on home soil at Lyon in 2023 as a 112th-ranked wildcard. At age 18 and 11 months, he became the youngest French champion since Gael Monfils won Sopot in 2005.

7. Carlos Alcaraz

“Teen phenom” seemed an understatement as Carlos Alcaraz set record after record in his first years on tour.

From his first title at Umag in 2021, the 18-year-old soon became the ATP’s youngest Masters 1000 champion at Miami. Still a month shy of his 19th birthday, he was also the youngest player to win the Madrid Open that season, before his Grand Slam breakthrough at the 2022 US Open.

It ensured an historic rise to becoming the youngest man to hold the world No.1 ranking – a position Alcaraz still held at the completion of his marquee year.

“It’s crazy for me. I’ve never thought that I was going to achieve something like that at 19 years old,” said the Spaniard. “Everything [has] come so fast … it’s something I dream[ed of] since I was a little kid.”

8. Holger Rune

As a former world No.1 junior who trained at the Patrick Mouratoglou Tennis Academy since age 13, Holger Rune made early headlines in tennis circles. Still, few expected his breakthrough at the Paris Masters 1000 tournament at age 19 in 2022.

After saving a trio of match points against three-time major champ Stan Wawrinka in the first round, Rune stunned Hubert Hurkacz, Andrey Rublev, Alcaraz, Felix Auger-Aliassime and Novak Djokovic in the final to become the first player in ATP history to claim five top-10 wins at a tournament other than the ATP Finals.

Rising to a peak of No.4 the following August, Rune quickly became the most accomplished Danish male player in history.

9. Emma Raducanu

British teenager Emma Raducanu completed a dream US Open debut in 2021, winning 10 straight matches to become the first WTA player to win a major title as a qualifier.

At age 18, she was the youngest woman to win a Grand Slam since Maria Sharapova at Wimbledon 2004.

In a fascinating turn, Raducanu overcame 19-year-old Leylah Fernandez in the first all-teenage Grand Slam final since Serena Williams defeated Martina Hingis at Flushing Meadows in 1999.

10. Iga Swiatek

While some players take gradual steps towards Grand Slam glory, others burst into the spotlight by making their first career title a major.

A 19-year-old Iga Swiatek was emphatically in the latter category as she completed a perfect campaign at Roland Garros in 2020, seizing the clay-court Slam without the loss of a set. Her victims included defending champion Simona Halep.

Swiatek was the youngest winner of the tournament since Rafael Nadal in 2005 (also 19) and the youngest women’s winner since Monica Seles (age 17) in 1992.

Proving it was no chance performance, the 23-year-old Swiatek is now a five-time Grand Slam champion – including four times in Paris –and has reigned at world No.1 for 125 weeks.

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