The first four months of the ATP and WTA seasons have not been short on great tennis, breakthrough performances and returns to form. Sure, the game's superstars have certainly won the biggest trophies: Novak Djokovic and Naomi Osaka were crowned Australian Open champions, and Ashleigh Barty and Stefanos Tsitsipas were among the those to win at 1000-level events so far in Miami and Monte Carlo, respectively - but what are some of the other early-season stories?
With hard-court tennis in the rearview mirror for now and the clay and grass seasons set to take center stage this spring and summer, here are five of the major takeaways the first quarter of the year.
Garbiñe Muguruza returns to form as WTA wins leader
While world No. 1 Barty leads the WTA with three titles, and Osaka was the year's first Grand Slam champion in Australia, the most consistent performer over the season's first four months has been a resurgent Garbiñe Muguruza.
With Hall of Famer and coach Conchita Martinez by her side, the Spaniard leads the women's circuit in wins with a 21-6 overall record, won her first title in two years at the Dubai Duty Free Tennis Championships in March and reached two other finals in seven tournaments played.
While she hasn't made moves in the rankings as of yet - she's currently sitting at world No. 13 - her level of play will assuredly earn her opportunities to climb higher and back into the Top 10 as the tours continue to adjust point allocation in the aftermath of the COVID-19 hiatus and subsequent ranking freezes.
On the biggest stage so far this season, Muguruza was a point away from ending Osaka's run at Melbourne Park in the fourth round before she ultimately was beaten in three sets. Had the eventual champion not staved off two match points for a 4-6, 6-4, 7-5 victory against her, the former world No. 1 would've certainly been in the mix for a third Grand Slam title with the tennis she showed Down Under.
Heading into the clay-court season, during which Muguruza was first crowned a Slam champion in Paris five years ago, could the 27-year-old be primed for another major run?
Lucky number 311: Djokovic makes history at the top of the rankings
After winning his 18th career Grand Slam title in Australia, Djokovic added another all-time accomplishment to his already legendary resume: most career weeks at world No. 1.
March 8 marked the start of the Serb's 311th career week at the top of the ATP rankings, passing Roger Federer's previous record of 310. He first reached world No. 1 on July 4, 2011, and has had five different stints at the top - including his current tenure that began on Feb. 3, 2020.
The ATP's Italian renaissance
In the aftermath of the successes of the last generation of Italian women, from Grand Slam champions Flavia Pennetta and Francesca Schiavone to singles finalists and doubles champions Sara Errani and Roberta Vinci, it seems as though the men's side is ready for a breakthrough.
Teenagers Jannik Sinner and Lorenzo Musetti have lit up the ATP rankings over the first three months of the season.
Sinner, 19, became the youngest finalist at the Miami Open since 2007, where he lost out to Polish No. 1 Hubert Hurkacz, himself just 24 years old. He started the year strongly as well, capturing the title at the Great Ocean Road Open, one of the events held in Melbourne ahead of the Australian Open.
Musetti, who turned 19 in at the start of March, had a career milestone at the end of the month: after reaching the semifinals as a qualifier in Acapulco, he debuted in the Top 100, becoming the youngest player in that ranking range. In Mexico, he earned his first Top 10 win against Diego Schwartzman, and also beat Frances Tiafoe and Grigor Dimitrov to reach the final four.
It's not just the teenagers who are winning, either. 25-year-old Lorenzo Sonego kicked off the clay-court season in style by sweeping the singles and doubles titles on home soil in Sardinia, while former US Open semifinalist and current world No. 10 Matteo Berrettini captured his first title since 2019 in Belgrade, Serbia. Berrettini, also 25, was forced out of the Australian Open due to an abdominal injury, and returned to the tour in Monte Carlo.
Biggest breakthroughs belong to Aslan Karatsev, Jessica Pegula
Daniil Medvedev called him Team Russia's "secret weapon" during February's ATP Cup, and 27-year-old Aslan Karatsev has lived up to the billing and beyond as the hottest player of the season so far.
After reaching for finals on the ATP Challenger Tour last year, which included two titles in August and September after the tour resumed, Karatsev seemed primed for next-level success — but no one could've predicted just how much.
To catch you up: ranked world No. 112 to begin the season, Karatsev qualified and went all the way to the semifinals at the Australian Open before bowing out to Djokovic. He followed that up by winning his first career ATP title in at the 500-level event in Dubai and a runner-up showing to Berrettini at the 250 in Belgrade, knocking nearly 100 places off his ranking in all.
Now ranked world No. 27, Karatsev has racked up wins against a who's who of the ATP's top names: after beating Schwartzman, Felix Auger-Aliassime and Dimitrov in Melbourne, he beat Sinner and Andrey Rublev in Dubai, and upset Djokovic on home soil in Serbia.
While there has been no true counterpart to the Russian on the women's side, the honor of biggest breakthrough in 2021 to date belongs to American Jessica Pegula. The pride of Buffalo, N.Y. began the season outside the Top 60, but after a run to her first Grand Slam quarterfinal at Melbourne Park and 17 wins on tour in all, she's become a player that no one wants to see in her draw.
(Especially, it seems, if you're former world No. 1 Karolina Pliskova. Pegula has beaten her three times in 2021 so far in Doha, Dubai and Miami.)
The 27-year-old is now ranked a career-high world No. 33 ahead of the clay-court season, and is certainly a contender to represent Team USA in Tokyo.
Youngsters and veterans alike arrive in the winner's circle
In all, 10 players from eight countries have already won their first tour-level singles title this season, including four teenagers*.
Including the aforementioned Karatsev in Dubai, the list of first-time champions includes:
- Argentina's Juan Manuel Cerundolo* – Cordoba
- Great Britain's Dan Evans – Melbourne 2
- Canada's Leylah Annie Fernandez* – Monterrey
- Russia's Veronika Kudermetova – Charleston, WTA 500
- Colombia's Maria Camila Osorio Serrano* – Bogota
- Australia's Alexei Popyrin – Singapore
- Australia's Astra Sharma – Charleston, WTA 250
- Spain's Sara Sorribes Tormo – Guadalajara
- Denmark's Clara Tauson* – Lyon
