A new tennis season brings a fresh start to so many aspects of the sport that we love.
There are also plenty of storylines that spill over into Australian Open 2025, including a host of burgeoning rivalries between the game's top stars.
FULL FIELD: Australian Open 2025 entry lists released
Here are 10 rivalries to watch for during the Summer of Tennis, and that we just may see play out in the latter stages of the year's first Grand Slam event.
Jannik Sinner v Carlos Alcaraz
Alcaraz leads 6-4
They split the two majors in 2024, but it was the Spaniard Alcaraz who swept his three meetings with the world No.1, including contender for the best (three-set) match of the year in an out-of-this world Beijing final that last three hours, 21 minutes and ended – fittingly – in a third-set tie-break.
Sinner and Alcaraz, with six majors now between them, have emerged as the frontrunners of men's tennis' new generation of stars, but their tennis matches themselves have that magic dust that no numbers can explain.
The velocity of shot, speed of foot and highlight reel-worthy baseline exchanges make this an already-great rivalry... and which may well still only be in its infancy.
Aryna Sabalenka v Iga Swiatek
Swiatek leads 8-4
It's a No.1-v-No.2 rivalry that has delivered on the women's side, with their own for-the-ages three-setter playing out in the Madrid final, many tennis aficionados' pick for match of the year on the WTA. (Swiatek won it.)
In this head-to-head, surface matters: Swiatek is an overwhelming 5-1 leader on red clay – Sabalenka won a nearly-as-compelling Madrid final in 2023 – but they are an even 3-3 on hard courts.
The two haven't met at a major since Swiatek rallied from a break down in the third set of their 2022 US Open semi, a tournament Iga would go on to win.
Sabalenka's improved serve and outright power make her especially vicious on hard courts, exemplified by her 6-3 6-3 breeze of Swiatek in the Cincinnati semis a few months ago.
Alexander Zverev v Daniil Medvedev
Medvedev leads 12-7
Can you believe the next time these two meet it will be match No.20 between them?
Zverev swept their opening four matches in 2016-2018, but since then it's been near one-way traffic as Medvedev has collected 12 of their 15 battles.
None are as memorable, perhaps, as Medvedev's back-from-the-brink effort at AO 2024, when Daniil clawed out of a two-sets-to-love deficit.
There is no love lost between these two, who have never been the closest of friends. But that AO meeting in January was their lone meeting in 2024, and Zverev has shown more consistency with his own serve, having once been handcuffed by double faults.
That five-setter in Rod Laver Arena was their first Grand Slam meeting; let's hope it's not their last.
Novak Djokovic v Carlos Alcaraz
Djokovic leads 4-3
Nearly every chapter of this seven-stanza showdown has been mouthwatering, from their first clash captured by Alcaraz in front of home fans in Madrid, to two Wimbledon finals, to Djokovic's dramatic stand for his historic Olympic gold in Paris.
READ MORE: Djokovic’s career CV complete with Olympic gold
Alcaraz has done what many in the generation just above him have failed to do: create uncertainty in Djokovic's mind. And he's done it with his out-of-this world athleticism from the baseline, which many call a modern-day version of Djokovic's game.
Sixteen years separate them in age. But on the court? There's little daylight.
Coco Gauff v Aryna Sabalenka
Gauff leads 5-4
These two have swept the hard court majors the last two seasons, with Gauff claiming the 2023 US Open and Sabalenka sweeping up two AOs and this year's US Open.
No match has seemed to play a bigger role in their nine meetings than that aforementioned 2023 championship clash on Arthur Ashe Stadium court, when Sabalenka looked in control only to see Gauff seize her chances with gutsy play.
Sabalenka exacted revenge in last year's semifinals in Melbourne, a high-quality affair that nearly went three sets.
If Sabalenka shows up at season's start as she has the last two years and Coco is able to carry her momentum from her recent WTA Finals win – watch out for that re-match.
Frances Tiafoe v Ben Shelton
Shelton leads 2-1
Are we on the cusp of another great generation of American men?
Taylor Fritz's run to the US Open final is the closest any US man has come to winning a major singles title in nearly 20 years, but Tiafoe, Shelton, Tommy Paul and Sebastian Korda are knocking on the door, too.
The dramatics have been high in just three outings between Tiafoe and Shelton, marked by that stunning US Open quarterfinal in 2023, won by Ben. But Tiafoe's exacted revenge in Queens this past year showcased his own ability to re-calibrate, teaming up with David Witt and re-committing to the kind of tennis that brought him into the Top 10.
Imagine if this rivalry is only in its beginning... Popcorn, please!
Jasmine Paolini v Elena Rybakina
Paolini leads 3-2
The plain height and game style differences already make this match-up intriguing, as Paolini's pivotal win in the French Open quarters brought it to another level this last year.
Rybakina wants to play in-charge, first-strike tennis, while Paolini will dig her heels in – no matter the surface.
That clash in Paris was a fork in the road, for both women. Paolini made consecutive Grand Slam singles finals en route to the standout season of her career, while Rybakina's stumble at Wimbledon – she lost to eventual champion Barbora Krejcikova in the semis – saw her barely win another match, going just 2-5 the rest of the season.
Qinwen Zheng v Coco Gauff
Gauff leads 2-0
You ask: Rivalry?
We retort: Did you see the WTA Finals championship match?
It is slotted right up there with Sabalenka-Swiatek in Madrid as women's match of the year, and further cemented both women in this generation of stars. The athleticism and power that both women possess is next-level, showcased in Riyadh and – we hope – many more times down the tennis road.
Pere Riba, Zheng's coach, was on Team Gauff when Coco won the US Open in 2023, so there are plenty of behind-the-scenes happenings in this one, too.
Novak Djokovic v Jannik Sinner
Tied at 4-4
You didn't think we forgot this one, did you?
The Australian Open 2024 winner took out the reigning champion a year ago in the semifinals inside Rod Laver Arena, in what many felt could be a changing-of-the-guard result. Djokovic is a 10-time AO champion who until that point had never lost a semifinal or final at Melbourne Park.
Between the two, Sinner has won three in a row, dating back to his Davis Cup heroics for Italy to cap off 2023.
Arguably the two best returners in men's tennis, this match-up offers video game-like movement from both gents as they glide across the court.
AO 2025 will be a first test for Sinner: How does he deal with "defending" his many 2024 successes? That's something Djokovic has built a career on.
Danielle Collins v Iga Swiatek
Swiatek leads 7-1
Yes, the head-to-head is lopsided, but two of their clashes have come Down Under, with Collins blasting through Swiatek to make the AO final in 2022 – where she'd lose a tight two-setter to Ash Barty – before the American slipped on her own banana peel from 4-1 up in the third, and love-40 up on Iga's serve at 3-4.
Collins would go on to have the season of her life, one she announced would be her last after that aforementioned loss to Swiatek in Melbourne.
But she's back, baby, and we can only hope that these two face one another from across the net once again. Because when Danielle is involved - you really never know. And that's the fun of it.