Within tennis analytics, it has become common to refer to the current period as the “Sincaras Era,” a reflection of how firmly Alcaraz and Sinner have seized control of the men’s game. Fans of Andrey Rublev have a favorite statistic: in the last two years, only one major event featured both Sinner and Alcaraz in the draw, yet neither won the title — Rublev did, in Madrid 2024.
Sinner’s gap (No. 2) over Zverev (No. 3) in the rankings is now larger than the gap between Zverev and the final player in the top tier. Still, Alcaraz insists: “Next season will be different. There will probably be another player who catches up to us, plays really well, and starts winning big matches.”
Who could he be referring to? Below is a data-driven assessment of the players most likely to challenge the two frontrunners.
The New Wave: Three 19-Year-Olds Already on the Rise
João Fonseca: a blistering forehand, but physical issues to solve
Fonseca’s first full ATP season put him firmly inside the top 30, with two titles — Basel (ATP 500) and Buenos Aires (ATP 250) — and a breakthrough win over Rublev at the Australian Open at age 18.
Key achievements:
- Two ATP titles (500 + 250)
- Round 3 at Roland Garros and Wimbledon
- Beat Rublev at a Slam at 18 (fourth-youngest ever to beat a top-10 player at a major)
- Won the 2024 Next Gen Finals
Fonseca is a baseline aggressor with one of the most explosive forehands on tour — structurally similar to Sinner’s, with full torso rotation and a pronounced elbow load.
But his limitations are clear:
- endurance issues in long matches,
- inconsistent movement,
- drop in intensity during extended rallies.
To reach the Alcaraz-Sinner level, Fonseca needs a full physical upgrade. Technically he is already close.
Learner Tien: tactical genius with a serve that holds him back
The American left-hander rose from No. 121 to No. 28 in a single year, won his first ATP title, and produced five top-10 wins — the most among under-21 players.
Highlights:
- ATP-250 champion in Metz
- ATP-500 finalist in Beijing
- 5 wins vs top-10 opponents
- Round of 16 at the Australian Open
Tien is stylistically the opposite of Fonseca: a lefty with a flat backhand, a wide tactical range, and an ability to disrupt rhythm with slices, net approaches, and sudden pace changes. He plays chess while others play checkers.
But there is a major problem:
- At 180 cm, his serve is statistically one of the weakest in the top 50.
- He wins only 61.5% of points on serve — fifth-worst among top-50 players.
The decision to hire Michael Chang speaks volumes: Chang maximized his career despite limited height and became a Slam champion. If Tien can upgrade his serve even moderately, he may be the most dangerous young match-up for both Alcaraz and Sinner.
Jakub Mensik: a huge serve, ultra-aggressive style — and injuries
Mensik’s rise culminated in a stunning title run at the Miami Masters, where he defeated Novak Djokovic in the final. His profile is built around raw power.
Key numbers:
- Miami Masters champion at 19
- Serve up to 225 km/h
- Solid two-handed backhand
- Highly aggressive “take-time-away” style
- 4 wins over top-10 players
But there are red flags:
- Repeated five-set losses despite leading 2–0 at Slams
- Limited court coverage due to his 196 cm frame
- Frequent injuries: withdrawals in Cincinnati, Beijing, Basel
Mensik’s ceiling is enormous, but only if he can stay healthy. Right now he resembles an early-career Zverev with a higher risk profile.
The Sincaras Age Group: Who Can Still Break Through?
Jack Draper: elite lefty potential overshadowed by fragility
Draper’s title run in Indian Wells — beating Fonseca, Fritz, Shelton, and Alcaraz — was one of the shocks of the season. It put him into the ATP top-10 for the first time.
Strengths:
- explosive lefty serve,
- heavy forehand,
- excellent return,
- strong matchup dynamics vs many right-handed power players.
But the injury history is long:
- hip issues (“a ticking time bomb,” as Draper calls it),
- chronic shoulder problems since 2023,
- bone bruise in the forearm that derailed the second half of the season.
A healthy Draper could challenge the top duo — but we have never seen him healthy for a full year.
Ben Shelton: a top-5 serve backed by a top-50 return
Shelton also won his first Masters title and soared to No. 5, qualifying for the ATP Finals for the first time. But his overall season has notable caveats:
- His Canadian Masters title did not feature Alcaraz, Sinner, Djokovic, or Draper.
- His non-Slam performance is unstable (66% win rate).
- His return numbers are problematic: he ranks just 47th in return points won (33.8%).
His serve alone keeps him competitive against most players — but against Sinner or Alcaraz the return deficit becomes decisive. Until he improves that area, he will remain a threat, not a true contender.
Lorenzo Musetti: artistic brilliance, structural weaknesses
Musetti climbed back into the top 10, made three finals, reached the Roland Garros semifinals, and beat three top-10 players during the clay season.
However:
- he wins only 64.4% of first-serve points — low for a top-10 player;
- one-handed backhand is increasingly vulnerable in the modern power game;
- he has not won a final in three seasons despite multiple chances.
Musetti’s upside is clear, but his limitations against top-tier ball-strikers make consistent breakthroughs unlikely.
Félix Auger-Aliassime: back in the contender conversation
Auger-Aliassime had one of the streakiest seasons on tour, but his finish was powerful: a US Open semifinal, a Paris Masters semifinal, and a late-season title in Brussels secured his place at the ATP Finals and a top-5 year-end ranking.
FAA at his best can challenge Alcaraz and Sinner: he possesses elite serve-plus-one patterns, athletic movement, and a strong baseline game. Consistency is the missing piece.
Holger Rune: big wins, bigger chaos
Rune is one of only two players of his generation to beat Alcaraz this season (in the Barcelona final). But his year was defined by disruptions:
- finished at No. 15;
- tore his Achilles late in the season;
- constant coaching changes, unstable scheduling, and emotional volatility.
Talent has never been Rune’s issue. Professional structure is.
Final Verdict: Who Can Actually Challenge Alcaraz and Sinner in 2026?
Based on game style, physical profile, age curve, and upward momentum, three names stand out:
1. João Fonseca
If his endurance improves, his power-baseline game could pressure both Sinner and Alcaraz — especially on faster courts.
2. Learner Tien
Lefty angles + tactical intelligence + variety. His matchup potential is huge if he lifts his serve to an acceptable level.
3. Félix Auger-Aliassime
Already proven capable of pushing the elite, and his late-season form suggests a resurgence.
Mensik and Draper have the raw tools but face durability questions. Shelton and Rune remain inconsistent in key structural aspects of their game.
