Who knows Katy Perry best? Not Katy Perry

Leave that to a fan.

Jimmy Kimmel invited "Katy Perry-phile" Emily on his Monday ABC late-night show to take on the real Katy Perry in a Katy Perry trivia game, Who Knows Katy?

"How well do you feel that you know Katy Perry?" Kimmel asked Perry, 29.

"Very well," she responded. "I'm ready to play me."

Emily was also ready. She talked about having a Perry-themed wall in her home, but her boyfriend made her take it down.

"At least you have a boyfriend," cracked Katy.

As Kimmel told them they had two minutes to play, Katy said, "This is the most narcissistic thing ever."

The first question was about Katy's parents' names and Emily beat Katy to the buzzer. Emily also answered the second question, too, correctly noting that Kelly Clarkson was the American Idol contestant for whom Katy had written two songs.

Perry cringed.

Guess who won?

That's right, the fan. But it was pretty close.