The strict security protocols governing the movements of President Sergio Mattarella of Italy dictate that he is not permitted to appear in the same location repeatedly. He is, in this respect and probably this respect alone, like lightning: He is not supposed to strike twice.

In rare circumstances, the rules can be bent. So last month, Mr. Mattarella was in attendance twice at track and field’s European Championships in Rome: once for the final of the men’s 100 meters, and once for the 4×100-meter relay. It seems the Italian president, like the rest of the country, cannot get enough of Marcell Jacobs.

A day after the second event, Mr. Mattarella met the 29-year-old Jacobs in person when Italy’s Olympic team was invited to the Quirinal, the presidential palace in Rome, for an official reception. The squad is a glittering one, including the champion high-jumper Gianmarco Tamberi and two of tennis’s brightest talents, Jasmine Paolini and Jannik Sinner.

There is no question, though, about which athlete is the headline act: Jacobs, the repurposed long jumper, son of an American father and an Italian mother, who in 2021 came out of nowhere to become the first Italian to reach the men’s Olympic 100-meter final, and then, 9.80 seconds later, the first to win it. Five days later, Italy won gold in the men’s relay. Jacobs ran the second leg.

Three years on, he has learned to handle his status well enough, happily obliging selfie hunters, graciously greeting well-wishers, coolly ignoring the awe-struck glances as he crosses the street. Still, he admits to finding it a little strange, a touch limiting, occasionally even slightly enervating.