And that was just for rehearsal. By Gaga couture standards, her ensemble may have constituted an "Oh, this old thing?" workaday outfit, but it demonstrated once again that there's no such thing in Gaga's world as a frump day.
She and Bennett ran through the title track from their recent duet album three times, backed by an acoustic jazz ensemble with piano, upright bass and drums, the baby grand accented with a couple of small, vintage table lamps.
FULL COVERAGE: Grammy Awards 2015
Gaga hustled backstage immediately after running through the song, which will be part of Sunday’s
"I'm a big believer in the Great American Songbook," Bennett, 88, said with that signature sandpaper rasp and looking sharp himself in a sport coat, slacks, crisp dark dress shirt and tie. "A lot of record companies call it 'old music' and I think that's absolutely ignorant. It's really the greatest music that ever came out of America."
"Most of these songs were introduced by, and written for, Fred Astaire," he said. "George Gershwin, Irving Berlin--the greatest composers adored Astaire so much."
In fact, Berlin wrote "Cheek to Cheek" for the 1935 Astaire-Ginger Rogers film musical "Top Hat."
"Everybody calls it 'The Great American Songbook,'" said Bennett, after noting that he also appeared on the first Grammy Awards telecast back in 1971. "I call it 'The Fred Astaire Songbook.'"
As for his vocal partner, Bennett said of Gaga: "She's a very good singer. She's not a flash in the pan. That's why I had to do these great standards. And it's really paying off because the album's so big. Now we're about to record an album of all Cole Porter songs. That'll be the second album."