But you know what's even more impressive then their perfect vocals? The fact that they only practiced it once.
Demi stopped by MTV News on Tuesday (June 24) and told us what went down behind-the-scenes before they took the stage at the Hollywood Bowl.
"When we were rehearsing the song he was like 'I'll take the first verse, you take the second verse,' and I was like 'OK.' So I listened to him sing the first verse and the first chorus and then it was my turn to sing and we were rehearsing in my dressing room," Demi said. "And I completely forgot all the words. I was like, 'I'm sorry, I'm really nervous."
But it doesn't seem like this will be the last time these two work together, since Demi teased that their much-anticipated collaboration is still in the works. They just need to find the time.
"We've talked about it for sure..." she said. "We discussed meeting up in London or wherever we are in the same place to write together, which has yet to happen."
But teaming up with Ed isn't the only duet Demi has on the horizon. On Monday the singer, who is premiering her video for "Really Don't Care" on Thursday, attended Logo TV's "Trailblazers" and met up with a certain former boy bander.
Demi tweeted out a cute pic with 'NSYNC's Lance Bass, who then responded by saying that "this duet is happening!!"
Wait a minute, so he's basically saying that all of our dreams going to come true, right?! Well, maybe.
"We were listening to A Great Big World sing 'Say Something' and he was like 'I want to perform this with someone so bad' and I go 'Let's do it,'" Demi said after adding that she grew up listening to 'NSYNC. "I totally invited myself, he was like 'Oh, ok' I was like, 'Sorry, we're doing it."