Tommy DeVito, a breakout sensation for the New York Giants, made the most of his moment in a prime-time spotlight on Monday, only to find himself upstaged — by his own agent.

During ESPN’s broadcast of Monday Night Football, which featured Mr. DeVito at quarterback for the Giants in a thrilling victory over the Green Bay Packers, it was impossible to miss the Rat Pack-era presence of his agent, Sean Stellato, who set the internet ablaze with his black fedora, pinstripe suit and smooch-filled celebration with Mr. DeVito’s father, Tom.

Mr. Stellato, 45, said in a telephone interview on Tuesday that he only grasped the magnitude of the moment when he began to receive text messages from his four daughters.

“They were blowing me up,” Mr. Stellato said. “They were like, ‘Daddy, this is crazy!’”

How crazy? In a simulcast of the game, Peyton Manning referred to Mr. Stellato as Johnny Fontane, the matinee idol and crooner from “The Godfather.” And the ultimate endorsement came on social media from Stevie Van Zandt, the celebrated musician and actor, who compared Mr. Stellato to Silvio, the character Mr. Van Zandt played on HBO’s “The Sopranos.”

“It’s been absolutely nuts,” Mr. Stellato said. “But you know what? We’re having fun with it.”

Mr. Stellato represents 12 N.F.L. players, including Mr. DeVito, an undrafted rookie whom the Giants summoned from the depths of their practice squad. Mr. DeVito has played up his Italian American heritage to great effect with Giants fans, while leading the team to three consecutive wins, and Mr. Stellato has added yet another layer to the overall aesthetic.

Before Monday’s game against the Packers, Mr. Stellato rummaged through his cedar closet full of 30 suits in search of something special.

“I knew it was going to be a dogfight, so I felt like I had to have some extra oomph,” he said.

Mr. Stellato went with a pinstripe suit from Mohan’s, the custom tailor on Madison Avenue; a black turtleneck from Paige; a fedora from Bellissimo; and a pair of gold Nike Air Force 1 sneakers, a gift from one of his clients. But make no mistake, Mr. Stellato’s outfit on Monday was nothing out of the ordinary.

“I mean, I’ve worn some wild stuff,” he said.

He recalled how his grandmother, Littizza Lillian Stellato, who lived with his family when he was growing up in Salem, Mass., had an outsize influence on his sense of style. She worked in the men’s department at Filene’s Basement, a longtime Boston-area institution, until she was 86, and often counseled her grandson on the importance of “looking the part,” Mr. Stellato said. She got him his first suit.

“My nonna,” he said. “She was my inspiration.”

As a teenager, Mr. Stellato sought to “look the part” by occasionally traversing the halls at Salem High School in white and pastel blazers, when he wasn’t starring at wide receiver for the football team. He described it as his “Miami Vice” phase. “And then it just kind of escalated,” he said.

At Marist College, he wore frosted tips under his football helmet. He walked the runway in a student fashion show. And he looked toward a future full of bespoke suits and gold bracelets.

Mr. Stellato was a young sports agent when a tailor offered him these words of wisdom: “You want to walk in the room and have someone say, ‘Who the eff is that guy?’” Mr. Stellato was trying to make his way in a competitive field, after all, and it would behoove him to try to stand out from the crowd.

He hardly needed the nudge. It was as if someone had told Jackson Pollock to use more paint.

“I love exotic leathers,” Mr. Stellato said. “I love ascots and fedoras.”

Mr. Stellato acknowledged that some critics have accused him of leaning in a bit too hard on Italian American stereotypes.

“People are like, ‘You can’t wear a fedora! You’ve got to be careful!’” Mr. Stellato said. “Listen, I’m not expressing certain things with slogans and wording on it. We’re talking about a fedora! It was a statement back in the day when Frank Sinatra was hot, back when Rocky was making ‘Rocky.’ So why can’t I have that as my fashion statement? I really admire the fedora look.”

A new inductee into the National Italian American Sports Hall of Fame, Mr. Stellato said he and Mr. DeVito had bonded in part over clothes.

“Tommy loves his fashion,” Mr. Stellato said. “He loves his gear. Maybe I’m a little louder at times, but we share that passion for clothing and lifestyle.”

And while Mr. Stellato’s wife, Krista, is largely supportive of his sartorial choices, she draws the line when he tries to pair one of his fedoras with a sweatsuit. His daughter Gianna, 16, also acts as a reality check.

“She’ll say, ‘Daddy, you can’t wear those pants! They’re too tight!’” Mr. Stellato said. “And I’ll be like, ‘All right, I’ll change them up.’”