Watch Charli XCX and Troye Sivan perform “1999” on The Tonight Show

Charli XCX and Troye Sivan wound the clock back nearly two decades last night with a performance of "1999" on Jimmy Fallon's Tonight Show. The pair performed their collaborative single on TV for the first time, channeling the Matrix vibes of the music video with slime-green lighting and plenty of leather. Check it out above.