The two first met when Presley returned from the US Armed Forces in 1960. Sinatra was just 19 years old back then.
Coming from humble beginnings, Elvis Presley became one of the biggest names in Rock 'n' Roll history in the mid-fifties. With his soulful voice and iconic style, e created a space for himself in the hearts of people. During his career, he delighted fans on radio, television, and on the silver screen.
On the other hand, Nancy Sinatra came from a family who already had a huge name in the industry. After all, she was the daughter of legendary singer, Frank Sinatra. Nevertheless, Sinatra overcame the pressure of maintaining her family name and grew up to be her own person with her 1966 hit single, These Boots Are Made for Walkin.
Looking at how popular these individuals were at the time, it can be expected of them to work together, and they did. The two starred in a movie titled Speedway, which was a box-office success. According to IMDb, Sinatra wasn't the first choice for the movie; it was Petula Clark. Annette Funicello was also considered for the role. However, Sinatra's popularity won over both.
When the movie released, the chemistry between Presley and the Somethin’ Stupid singer shocked everyone and left them thinking if they were more than just co-stars. It was possible, or it could have been because of their past history.
After Presley was discharged from the US Armed Forces in 1960, a 19-year-old Sinatra welcomed him at the airport and invites him to Frank's show, according to The Guardian. Even though Frank Sinatra had previously dubbed Presley's music as "a rancid-smelling aphrodisiac," he set aside all his feelings and invited the King of Rock 'n' Roll to his regular talk show, which was retitled to Frank Sinatra's Welcome Home Party for Elvis Presley. This was Presley's civilian life.
Sinatra described the crooner as “one of the funniest people ever," on her official blog on NancySinatra.com, as cited by Express UK. “His humor was silly and self-deprecating. He made fun of himself which is a very endearing quality to have. We did have fun, that’s for sure.” She told The Guardian that like all the other girls, she too was a fan of Presley. “I was like every girl my age – head over heels in love.”
They met again on the sets of Norman Taurog’s Speedway in 1968, and that's how their friendship began. While Presley played a NASCAR racer, Steve Grayson, with a gambling habit, Sinatra played his agent who keeps him in check but eventually falls for him in the process.
Recalling their friendship, Sinatra admitted that there was "flirting" between them but it was platonic. “There was flirting, but just friendly flirting. Actually, we were like The Katzenjammer Kids,” she divulged. “We used to ride a bicycle built for two around the studio, the MGM lot. Speedway was Elvis at his peak, in his prime. He was beautiful."
Elaborating more on the time they spent together while talking to The Daily Mail, she said, "When we did our movie he had a tandem made for us. He’d say, 'Nancy, let’s go for a ride,' and then off we’d go and within seconds all these Elvis fans would descend on us and we wouldn’t get more than a few minutes cycling done. But it was fun. He loved life, he loved to laugh."
Praising the Can't Help Falling in Love singer, Sinatra continued, “I feel kind of sorry for those who don’t get Elvis. A little more open-minded study and they would discover a fabulous soul who contributed plenty to the history of American music. He was the best at what he did and, like Frank, there will never be another to equal him. I treasure him. You will never know how much I miss him.”
Even though the crooner had his fair share of relationships with women, he married the one he gave his heart to forever, Priscilla Presley. They tied the knot in 1967. It was during Speedway's shoot, Priscilla gave birth to Presley's only daughter, Lisa Marie Presley.
References:
https://www.imdb.com/title/tt0063634/trivia
https://www.theguardian.com/music/2010/mar/04/elvis-presley-army-rocknroll
https://www.nancysinatra.com/about
https://www.theguardian.com/music/2008/jun/02/popandrock.usa