But not long before the MC spit his verse alongside the pop superstar, MTV News caught up with him on the red carpet, where he shared his marching orders for the gig.
"It's really Justin Bieber's performance, and I'm just guest performing," he said. "It's really his show. I'm not going to take anything away from it. I just come out do my verse, keep it player, keep it moving, and it's fun though."
Sean added that he was looking forward to some of that TCA attention. "It's tight to be able to get to work with him," he continued. "He's Justin Bieber ... arguably one of the biggest artists in the world. It's tight I get to share some light with him."
The twosome recently shot a video for the Believe single. They worked with Anthony Mandler on the clip, which, according to a recently released screen grab, will leave Bieber a bit roughed up. Little is known about the story line, and Mandler's only tease so far is one tweet: "It's a story of love.... #believe."
With Bieber's Believe Tour on the horizon, Sean isn't ruling out any surprise cameos. That means the twosome have until September, when the tour begins, to plot out some special performances.
"I don't know about the tour, but maybe some special cities. I might have to pop up in Detroit," he said. "I'm pretty sure that tour's going to be crazy."