“Lady Gaga is going to sing with me,” Tony Bennett said on the phone. “It’s a secret!” We were in Montreal on July 1. Tony was singing that night in his favorite hall at his favorite jazz fest. But there was an added attraction: the most famous pop singer in the world singing with the living legend of the Great American Songbook. “We’re going to surprise everyone. Come to the soundcheck, Bennett loved how much Gaga loved singing “The Lady Is A Tramp” on his 2011 album Duets II. Dancing in the accompanying music video. Curvy in tight black lace. Her hairs bouffant of swirling teal. Dancing over to Bennett’s mic to sing “I’m so broke!” “But it’s OK,” he replies, his face beaming. Delighted. “She loves jazz,” Bennett had said back then. “And she’s really good!” The pair has now recorded an entire album of standards, Cheek To Cheek (Streamline/ Interscope/Columbia), and at the Montreal Jazz Festival they were sneak-previewing several of the songs: Gaga singing “Lush Life” solo and the two vocalists doing duets of “But Beautiful” and “It Don’t Mean A Thing If It Ain’t Got That Swing, “Doo-waht Doo-waht” they swung.

Backstage at the Salle Wilfrid-Pelletier, they came for the soundcheck, Bennett in a green tracksuit, Gaga in a tight cocktail dress with a drape of black across the bodice. Looking swanky for a partyon the moon. She smiled and, being in a city so culturally French, kissed us on both cheeks. Bennett had introduced us several weeks before at his apartment in Manhattan. (Gaga certainly has a larger-than-life persona, but I’ve rarely encountered anyone so immediately and even radiantly nice. “It’s no wonder,” I’ve thought ever since, “that the nicest guy in show biz gets along with Gaga.”) They rehearsed in Montreal with Bennett’s quartet, with master accompanist Mike Renzi at the piano. And what amazed me at once were Gaga’s chops, even when projecting a swooping chorus up to the balcony. And she can sing in a hush. So quietly tender. Especially on a heart breaker like “Lush Life, Festival photographers were not supposed to shoot at the show that evening, but when Bennett surprisingly called Gaga to the stage, to a roaring tumult of cheers, cellphone cameras clicked all around the hall. And by the next morning, Bennett and Gaga -- as depicted in a wobbling blur from the balcony -- were singing together on YouTube.

“We were both doing a benefit," Bennett recalled, discussing the origins of the Cheek To Cheek album. They were singing at the 2011 gala for The Robin Hood Foundation. “We raised millions of dollars that night for the impoverished people of New York.” That night Gaga sang “Orange Colored Sky,” the song that Nat “King” Cole recorded with Stan Kenton, with the famous chorus “Flash! Bam! Alakazam!” It’s a perfect fit for an extroverted swinger like Lady Gaga. “I was knocked out when I heard the reaction of the audience to her,” Bennett said. “I’d never heard people enjoy anything that much in my life. I couldn’t believe the wonderful reaction she gets from the audience. They adore her!”

“When I found out that Tony wanted to meet me, my mother and I screamed,” Gaga recalled. “We were backstage at the Robin Hood event. My mother and I were in a trailer. We screamed—and we started to fix our hair! My father started laugh-ing and shaking his head. We ran to meet Mr. Bennett, Oh, my gosh, it was a wonderful thine “When I met her,” Bennett said, “she couldn’t get over that I was backstage to say hello to her parents and her. And I said to her, I'd love to do an album.’ And she said, tees do it,’ She’s that quick about things. When she says something, she means it, Not that recording together happened as quickly.

“Usually, it takes a couple of months for me to think about an album, but when I do it, it, four days,” said Tony. “This album took a whole year -- because of her fantastic touring all over the world. Whenever she had a chance, that’s when we did it, During the recording sessions, Bennett, quartet played on some of the songs. Gaga’s jazz friends, the quintet of trumpeter Brian Newman, were also featured. An orchestra was arranged by Jorge Calandrelli. Brass was arranged by Marion Evans. And contributing solos were saxophonist Joe Lovano, trumpeter George Rabbai, pianist Tom Rainier and, playing flute on “Nature Boy,” the late Paul Horn.

By September, two singles had been released: “Anything Goes” and “I Can’t Give You Anything But Love, Both topped the download charts. Additionally, “Nature Boy” was released for streaming on Gaga’s Vevo channel. The album Cheek To Cheek includes 11 songs on the standard version and 15 on the deluxe version, with different bonus tracks on the albums from Target, HSN or iTunes. There, also a 180-gram vinyl version. Plus, there are videos of the songs and a behind-the-scenes broadcast special for HSN. On July 28, Bennett and Gaga sang together at Frederick P. Rose Hall in Jazz at Lincoln Center. The concert was taped for a Great Performances special that will be broadcast on PBS on Oct. 24. That they were ever able to coincide enough to record Cheek To Cheek was phenomenal. The past couple of years, Bennett and his new Lady both have been … busy.

Gaga’s third album, ARTPOP, topped the Billboard 200 album chart, and she’s toured worldwide. She was the last artist to play the legendary Roseland Ballroom, concluding a week-long residency with an April 7 concert—the final concert for the famed, 95-year-old venue. She also hosted Saturday Night Live and a Thanksgiving TV special with The Muppets. She acted in a couple of movies for director Robert Rodriguez (Machete Kills and Frank Miller’s Sin City: A Dame To Kill For). And she’s been quite active as a philanthropist, including her own Born This Way Foundation, a nonprofit that encourages youth empowerment, and as an advocate for LGBT rights.

Bennett's most recent collaborative albums -- Duets: An American Classic, Duets II and his encounters with stars of Latin music, Viva Duets -- all have been international best-sellers. Another album he made last year (yet to be released) consists of Jerome Kern compositions recorded with pianists Bill Charlap and Renee Rosnes. He also released the massive box set The Complete Collection, his life in jazz and song on an astounding 76 CDs. He still tours. “I have enough -- I don’t have to sing,” Bennett explained, “but I love to sing, With his wife, Susan Benedetto, he heads Exploring The Arts, a nonprofit that supports arts education in schools all around New York City and in Los Angeles.

Bennett and Gaga also collaborated on another benefit. Tony Bennett the singer is, in his other artistic life, Anthony Benedetto the painter. He paints every day if he can. He sketches almost constantly. Not long after they’d starting working together, Tony sketched Gaga nude (except for very high heels) and the charcoal-on-paper portrait was auctioned off for $30,000 to benefit Exploring The Arts and the Born This Way Foundation.

Famed photographer Annie Leibovitz shot the scene in Bennett’s atelier for Vanity Fair magazine. And another piece of Benedetto artwork -- his portrait of Miles Davie trumpet -- now actually decorates Gaga herself: as a tattoo, on the inner part of her right arm. For this DownBeat feature, I talked with Bennett in his studio, overlooking Central Park. Bennett’s landscape of the park, along with his portrait of Duke Ellington, are just two of the paintings that he has donated to the Smithsonian. Around us in his studio were a new watercolor of a surrey in the park and portraits of Joe Lovano and Dizzy Gillespie.