One former tennis star immediately phoned his agent to quit the sport after losing to a teenage Sinner at the Rome Masters

Jannik Sinner once played a match so commanding that it sent his opponent into early retirement. Alongside fellow trophy-magnet Carlos Alcaraz , Sinner has become one of the two dominant forces in men's tennis, claiming the last eight Grand Slam titles and challenging the legacies of Novak Djokovic , Rafael Nadal and Roger Federer .

While not as hyped as Alcaraz during his teenage years, Sinner still made a big impact. At the 2019 Rome Masters , 17-year-old Sinner - then ranked No. 263 in the world - stunned former American No. 1 Steve Johnson in the first round.

Despite having only two ATP matches under his belt at the time, Sinner triumphed in thre

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