The King of Swag is also the reigning Pop Clash champ! Last week, Justin Bieber's 'Heartbreaker' took the title from Britney Spears' 'Work Bitch.' Now JB is up against Katy Perry's 'Unconditionally.'

Justin Bieber gets in touch with his soulful side in 'Heartbreaker.' The singer shows his vulnerable side in the slow jam, as he tries to convince his lady that he's trying to be a better man. It's okay, Justin, we love you in spite of your imperfections.

Katy Perry is definitely setting a trend of positivity in her music! While 'Roar' advocated standing up for herself, 'Unconditionally' is all about loving someone despite his or her faults. The power ballad shows off Katy's vocals and packs a ton of emotion!

Who should win this week's Pop Clash: Justin or Katy? You can vote once an hour until the polls close at 3PM ET on Oct. 28.

Listen to Justin Bieber, 'Heartbreaker'

Watch the Lyric Video for Katy Perry, 'Unconditionally'