Barbra Streisand Performs a Medley with Jimmy Fallon

ET's Nancy O'Dell sat down for an extensive interview with Barbra Streisand-- a TV moment you don't want to miss tonight-- but the legend also had a big first on Monday's Tonight Show. For the first time in 50 years, Streisand returned to the late-night program, and gave two amazing performances.

Jimmy Fallon didn't take her appearance on the program lightly and dedicated the entire Monday Tonight Show to the legend. Introducing her as "one of the biggest stars in the history of show business," he performed alongside her for an opening number where they sang some of her tracks off her upcoming duets album Partners, out today, Sept. 16.

Fallon, of course, used his impressions during the performance, including Elvis Presley ("Love Me Tender"), Blake Shelton ("I'd Want it to be You") and Michael Buble ("It Had to Be You").

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Streisand got pretty candid with ET about singing with such great men in music. "Sometimes if you're lucky, you find that certain someone," she doted on country crooner, Blake Shelton.

As for Elvis, she recalled meeting him back in 1969, but said she never looked up because she was too nervous. "I mean this guy walks in with two bodyguards, and he had pitch black hair, and a big silver belt," she said of first seeing the King of Rock and Roll. "And we sat in my dressing room and I was, I guess because I was scared, I started polishing my nails."

For Fallon's interview portion of the show, the host insisted that Streisand sit behind the desk. She chatted about her album, which also features Stevie Wonder and Billy Joel, and how her stage fright kept her from performing music live for nearly three decades.

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The musical guest of the evening was, you guessed it, Streisand. The 72-year-old conquered her stage fright and performed "Come Rain or Shine" solo, though on the album she's accompanied by John Mayer.

Here's a fashion flashback of Babs, and you gotta watch ET's MUST-SEE interview with the icon.