Justin Bieber was back with "The Late Late Show," but this time he gave the audience members the ultimate surprise by replacing James Corden for the opening monologue instead of singing carpool karaoke with him. When the curtains opened, it was the 21-year-old singer who walked out onto the stage instead of Corden, and the crowd went absolutely nuts.

"Let's do this," Bieber said. "We got a big show."

He then went right into a stand-up comedy routine, joking about how Obama revealed his favorite song of the year and how Hilary Clinton's favorite song is probably "Whatever Will Get You to Like Me." He even joked that Yahoo CEO Marissa Mayer's new identical twin babies probably already have Gmail accounts.

Just as he was really getting into it, Corden stormed onto the stage in a bathrobe with a towel on his head. "What the...What is going on?" he yelled at Bieber. "I'm just getting in the bath. I've lit a scented candle. I hear the music playing. Clearly I'm not ready. Reggie, why did you start the music?"

"You told me to play the music, and that's what we did," his bandleader Reggie Watts explained, to which Corden said, "That's not me, that's Justin Bieber!"

"James, you look exactly alike," Watts said. "How am I supposed to tell the difference?"

"Yes, I know we look almost identical," Corden replied.

"That's not true," Bieber quickly added in. "That's not true at all."

Bieber then apologized, to which Corden says, "Well, it's too late to say sorry," referencing Bieber's hit song, to which Bieber replied, "What do you mean?," referencing yet another one of his hit songs.

"Well, now you're just naming your own songs," Corden jokes back. "That's pathetic."

Eventually, Corden gives in and lets him continue hosting the show. Watch the hilarious clip below!