Tommy Hilfiger achieved the first step. He secured 14-time Grand slam Tennis champion Rafael Nadal to endorse his underwear.

The hard part was building a campaign Nadal would approve. Hilfiger's advertising partner, Trey Laird, advised the brand develop sex appeal to go along with its traditional, family-oriented image.

Rafael Nadal Suit

"What if Rafa's in the locker room and he's taking off his briefs?" Hilfiger remembers Laird asking him. "I said 'I don't think we can do that.'"

Laird went ahead with a storyboard and filmed a rough cut. "I don't think he's going to want to take off his underwear in front of a whole camera crew," Hilfiger warned Laird.

Laird and Hilfiger showed Nadal, 29, the video and held their breath. They got the answer they wanted.

"At the beginning, I thought it would be crazy, but when I was checking on the videos, I felt comfortable with it," Nadal says. "I like it. There was a great team around when we were shooting."

Nadal obviously felt comfortable in front of the team. In the ad, filmed in Mallorca, shows Nadal nearly taking his underwear off.

Hilfiger says he met Nadal more than ten years ago, and the Spaniard was wearing Hilfiger's eponymous brand at the time. They have kept up a personal relationship for the past decade.

Nadal's name is added to a list of previous Tommy Hilfiger celebrity models that include David Bowie, Lenny Kravitz and Britney Spears. However, Nadal's tennis success gives him a unique dimension.

Rafael And Tommy

"He is a global icon," Hilfiger says. "He's known all over the world. He's respected all over the world. I really believe if we were to have used a model, for instance, people would look at the ad, and say, oh, there's a nice model, but there wouldn't be any interest or intrigue. I think when you have a personality representing a brand, there's something else there."

To publicize Tommy Hilfiger's new line of underwear, tailored suits and fragrance, the brand put up a makeshift tennis court in New York City's Bryant Park. Nadal, along with models including Hannah Davis and Chanel Iman, played a game of strip tennis. They started with full Tommy Hilfiger attire, but only Nadal was left with his suit on. Jane Lynch hosted the match with actress Lake Bell by her side. Martha Stewart and actor Nat Wolff were also in attendance.

Nadal says he felt "comfortable" with the event that left him shirtless. His stripping was more to fit in with his fellow competitors than for losing purposes.

"I try to enjoy a different thing, a new world, a different experience," Nadal says. "With all experiences, I'm going to learn something in life, and now, I have the experience to know the world of fashion and it's something interesting for me."

Nadal uses his tennis as a tool to become well-educated, something he says he values. He does not let his outside interests thwart his game.

"I already practice two hours and 15 minutes in the morning before coming here," Nadal said late Tuesday afternoon after playing strip tennis. "All the promotions, all the work outside of tennis is great. If you have that, good news. It's because people have an interest of you if you have all these things. All the things that happen outside the court won't affect inside the court."

Nadal Shirtless

On the court, Nadal cannot deny he is having one of his poorer seasons. A nagging wrist injury kept Nadal out of Flushing last year, and Nadal dropped to No. 10 in the world in June, his lowest since April 2005. He is now No. 8 and he did not surpass the quarterfinals in any of the year's first three majors.

Is there something different about you, Rafa?

"No, I am still Rafa," he says. "I still live in the same place. Winning or losing is part of the game. Because of the victories, I didn't change. Because of the losses, I didn't change. It doesn't affect my personality and my way to see the things in life. Tennis is just a game."

A game Nadal was very good at for a very long time. Numbers suggest Nadal may be on the decline. His drought of four straight majors entered without a title is his longest since he won his first, the 2005 French Open.

Two years ago, Nadal came into Flushing on the flip side. He won his two hard court tune-ups in Montreal and Cincinnati before dropping just two sets at the U.S. Open. He finished the season as the world No. 1.

Nadal calls 2013 a "magic year." "I was playing at the highest level I played on hard court," he says.

Nadal had mediocre outings in Montreal and Cincinnati this month, reaching the quarterfinals and third round, respectively. He thinks his confidence is building though, and a high U.S. Open finish can boost his season.

"It's important for me to finish the year in the top eight to start the next year with the possibility of being high-seeded from the beginning," he says.

Tommy Hilfiger Group

Next Monday, Nadal, seeded eighth, will start his pursuit of his third U.S. Open title.

In the meantime, he will see pictures and videos of himself in underwear floating around the Internet and New York City billboards.

More Tennis: A History Of Drake And Serena Williams

-- Follow Jeffrey Eisenband on Twitter @JeffEisenband.

Story continues below