5 Australian Open breakout stars to watch in 2025: ft Joao Fonseca, Learner Tien

The Australian Open is done and dusted and while Madison Keys and Jannik Sinner are receiving the most plaudits, a few other stars will be celebrating career-changing tournaments.
Here, we look at five Australian Open breakout stars to keep an eye on across the rest of 2025.
Joao Fonseca
Few stories in the opening days of the Australian Open were as big as Fonseca’s dominant straight-sets win over ninth seed Andrey Rublev.
Having come through qualifying to reach the main draw of a Slam for the first time, the Brazilian demonstrated why he is one of the ATP’s hottest prospects in a 7-6(1), 6-3, 7-6(5) triumph.
Fonseca would then lose in round two to Lorenzo Sonego but this was undoubtedly a huge breakthrough for the 18-year-old, who has broken into the top 100 of the ATP Rankings for the first time.
Now at 99th in the world, Fonseca will become a more regular feature on the main ATP Tour in 2025.
There will certainly be ups and downs for the teenager over the coming months, though it will be fascinating to see just how far he can climb.
Eva Lys
Having initially lost in Australian Open qualifying, Lys’ run to the fourth round of the women’s singles draw was one of the best stories of the tournament.
The German had only one major match win to her name heading into the tournament but took her chance in style, becoming just the sixth lucky loser to reach the round of 16 at a women’s Grand Slam event.
Aged 23, Lys is not a new prodigy breaking through but is still comparatively inexperienced compared to many her age, and this run in Melbourne was a clear demonstration of her potential.
Having moved up 37 spots to 91st in the WTA Rankings – a new career high – all eyes will be on what she can go on to achieve in 2025.
Learner Tien
The biggest breakthrough performer of the whole tournament was surely Tien, who came through qualifying to reach the fourth round in Melbourne.
It was his win over fifth seed and three-time finalist Daniil Medvedev that understandably attracted the most attention, outlasting the Russian physically and mentally to prevail in a fifth-set breaker.
The American leapt 41 spots in the ATP Rankings to a new career-high of 80th thanks to his run in Melbourne, which also saw him defeat Corentin Moutet before a loss to Sonego.
Tien does not possess the raw power of the likes of Fonseca but possesses a fine tactical ability that should stand him in good stead as he looks to back up his Australian Open exploits.
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Olga Danilovic
Danilovic has reached the fourth round of a Grand Slam before, but her run to the second week in Melbourne suggests she is a player few would fancy playing across the remainder of 2025.
Long recognised as a junior prodigy, the Serbian dismantled 25th seed Liudmila Samsonova in the second round, before a stunning 7-6(3), 6-1 over seventh seed Jessica Pegula in round three.
Though she fell in the fourth round to Paula Badosa, the 24-year-old has moved up to a new career-high of 41st and could easily find herself seeded at Roland Garros if she continues her current trajectory.
With clean, aggressive ballstriking and growing confidence, Danilovic could be in line for a long-awaited rise to the top.
Alex Michelsen
Michelsen’s progression up the ATP Rankings in recent months has been incredibly solid, and he can now call himself a top-40 player after his run to the fourth round.
The American star struggled in his exit to Alex de Minaur but had been hugely impressive up until that point, dispatching 11th seed Stefanos Tsitsipas in round one and 19th seed Karen Khachanov in round three.
US men’s tennis is a crowded field at the moment but Michelsen is starting to make his mark and achieved a better result Down Under than higher-ranked compatriots such as Taylor Fritz and Frances Tiafoe.
Michelsen’s mental and physical improvements in recent months are clear to see and his run in Melbourne will likely propel him further up the ATP Rankings.