Taylor Swift selena gomez
Singer-songwriters Taylor Swift and Selena Gomez perform onstage during The 1989 World Tour Live In Los Angeles at the Staples Center on Aug. 26, 2015 in Los Angeles. Christopher Polk—TAS/Getty Images

Watch Justin Timberlake and Selena Gomez Grace Taylor Swift's Stage

Aug 27, 2015

At this point in her 1989 tour, Taylor Swift has welcomed everyone from Cara Delevingne to Julia Roberts to Chris Rock to Lisa Kudrow to her esteemed stage. Her five-night engagement at LA’s Staples Center has been particularly celeb-stacked—this week, she’s sung “You Oughta Know” with Alanis Morissette, gone spangle-for-spangle with Ellen DeGeneres, performed “Dreams” with Beck and St. Vincent and duetted with John Legend on “All Of Me.” Last night, for her final trick, Swift brought out the only two celebrities—nay, people—left on Earth that she has yet to harmonize with in front of thousands of iPhones: Justin Timberlake and Selena Gomez.

First up, Verified T. Swift Bestie Gomez took the stage in a pair of Swift-esque hotpants for the debut live performance of her new single “Good For You,” which Swift called “the song of the summer.”

Later, Timberlake—who, fun fact, stopped by The Ellen DeGeneres Show in 2008 to surprise an utterly lovestruck teenage Swift as she wore a glittery LBD in the daytime—joined Swift for a rousing rendition of his hit single “Mirrors.” In a nod to how far they’ve both come since awkwardly discussing gender relations on Ellen, Swift explained, “Justin hasn’t performed since he became a dad, so I’m just honored that this is his first performance.”

2006 CMT Music Awards - Arrivals
VIEW GALLERY | 34 PHOTOS
Taylor Swift arrives at the 2006 CMT Music Awards at the Curb Event Center at Belmont University in Nashville, Tennessee.John Shearer—WireImage/Getty Images
2006 CMT Music Awards - Arrivals
2007 CMT Music Awards - Red Carpet
42nd Annual Academy Of Country Music Awards - Show
2008 ACM New Artists Party For A Cause
Taylor Swift and Michelle Williams Visit MTV's "TRL" - June 16, 2008
The 42nd Annual CMA Awards - Arrivals
CNN Heroes "An All-Star Tribute" 2008
Saturday Night Live
The Brit Awards 2009 - Arrivals
44th Annual Academy Of Country Music Awards All-Star Jam
Taylor Swift in Concert
2009 MTV Video Music Awards - Arrivals
The 43rd Annual CMA Awards - Show
The 52nd Annual GRAMMY Awards - Show
Taylor Swift drops one of her awards dur
Taylor Swift 13 hours on the 13th. & some songs
Grand Ole Opry 85th Birthday Bash
44th Annual CMA Awards - Show
taylor Swift attends the 'Alexander McQu
2012 MTV Video Music Awards - Show
BBC Radio 1 Teen Awards - Show
BBC Radio 1 Teen Awards - Show
Taylor Swift Switches On Westfield London Christmas Lights
26th Annual ARIA Awards 2012 - Arrivals
26th Annual ARIA Awards 2012 - Show
KIIS FM's Jingle Ball 2012 - Night 1 - Show
Taylor Swift At Gillette Stadium
2013 Victoria's Secret Fashion Show - Show
Taylor Swift Lives In Shanghai
2014 American Music Awards - Show
2014 American Music Awards - Roaming Show
The Voice - Season 7
2014 Victoria's Secret Fashion Show - Show
KIIS FM's Jingle Ball 2014  Powered by LINE  - Show
Taylor Swift arrives at the 2006 CMT Music Awards at the Curb Event Center at Belmont University in Nashville, Tennessee.
John Shearer—WireImage/Getty Images
1 of 34
All products and services featured are based solely on editorial selection. TIME may receive compensation for some links to products and services on this website.