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.

“I was winning one test, for sure,” the 6-foot-5 Berrettini said this week. “My height. I was the tallest.”

Santopadre convinced Berrettini that in the years to come he would mature in mind and body, and blossom into a player equipped to compete against men in four-hour tests of will in front of thousands of spectators.