Karsten Moran for The New York Times
Matteo Berrettini rolled his eyes and shook his head as he recalled a humbling moment in his mid-teens. He was at an Italian tennis training facility going through a battery of athletic tests — comparing him with other young players in running, jumping, reaction time and stamina.
It did not go well. Berrettini, now 23, said he finished last in almost every measurement. Afterward he was distraught enough to ask his coach, the former top 100 player Vincenzo Santopadre, whether he should even carry on.
Santopadre pointed out that his pupil had not lost every competition that day.