Trainor looked stunning in a shimmering gold mini-dress, while Puth tickled the ivories in a black leather jacket. Taking a cue from the pair's music video, released in April, they surrounded themselves with couples engaged in full-out makeout sessions. By the end of the set, Puth and Trainor joined in on the fun with an uncomfortably long (15 seconds on air! Yes, we counted!), very passionate kiss.
Yep -- Puth even got a solid butt-grab in there, too.
Puth confessed to some pre-show nerves on the red carpet with Entertainment Tonight. "I'm keeping calm right now, but when I get on stage, I'm knocking over that piano bench and going, 'Ahh! Let it go,'" he said.
This show wasn't the first time the duo has gotten cozy in front of a camera. Trainor Instagrammed this sweet snap from their AMAs rehearsal earlier this week.
Just last month, Trainor sat down with ET and opened up about the struggles of being single and famous.
"Even without the fame, if I walk into a room -- I kind of have that personality where I just take over the room," she said. "I'm like, 'Hey! M-Train's here! What's up!' Which is very intimidating for guys alone, and then on top of [that] being a pop star -- I get it. I don't think they're less interested, I think they're just intimidated."
Trainor confirmed that she wasn't currently dating, but also wasn't in a rush to settle down.
"It's fine, I'll wait for him," she jokes. "[I'm looking for] someone who's a gentleman, someone who opens that door. A dude pulled out a chair for me the other day and I was like, 'Whoa! OK, nice!' That's new for me. I liked it. And if they're funny, that's awesome."