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Watch Taylor Swift And A Rock And Roll Hall Of Famer Chase 'Satisfaction' Onstage

Please welcome to the stage...all the badassery.

At this point, it's news when Taylor Swift doesn't surprise her 1989 World Tour audiences with unexpected musical guests (or non-musical guests, too). But Saturday's special guests, on the second night in Tay's onetime home city of Nashville, are definitely newsworthy -- even among the veritable #HolySquad of 1989 tour alums.

As bright light cannons blasted, Mick Jagger, the charismatic (potentially immortal) frontman of The Rolling Stones, joined Tay for a rousing rendition for the seminal 1965 Stones hit "(I Can't Get No) Satisfaction."

Swift enthusiastically tweeted a microphone emoji and the words "*drops mic*" after the show because, you know, the guy's a legend.

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But of course, the 1989 World Tour is never not trying to top itself. And the surprises didn't stop there. Tay also brought Leona Lewis to the stage for a rafter-raising performance of her magnificent 2007 hit "Bleeding Love."

Night one in Nashville wasn't a quiet affair, either. Aerosmith's Steven Tyler joined to sing your favorite 1998 song to cry to, "I Don't Want To Miss A Thing"... newbie/prospective Tay lil' sister Kelsea Ballerini joined for duet on "Love Me Like You Mean It"...

...and bluegrass singer-songwriter Alison Krauss popped up for "When You Say Nothing At All."

The juggernaut 1989 World Tour rolls on until December, when we can only imagine Tay's final guest will be Santa Claus himself.