Once again, Demi Lovato owned Pop Clash! Last round, her 'Nightingale' beat out Fifth Harmony's 'Worth It.' This week, Demi is up against Rihanna's 'FourFiveSeconds.' Which song should win the Pop Clash?

Demi is at it again -- giving us all of the feels with her insanely amazing voice. 'Nightingale' is everything we love about a Demi ballad. It's sincere, stripped-back and so poignant. 'Nightingale' strikes a particular chord with us, as it shows the a vulnerable side of the singer. It's no wonder that this is a fan favorite.

Speaking of songs we can't get enough of, RIhanna's newest song is set to be an instant classic. 'FourFiveSeconds,' featuring Kanye West and Paul McCartney, is a totally new sound for the singer. RiRi's fans love her energetic dance anthems, but the acoustic guitar-driven track proves she can hold down a laid-back tune as well.

Which song should win the Pop Clash? You can vote for Demi's 'Nightingale' or Rihanna's 'FourFiveSeconds' once an hour until the polls close at 3PM ET on Feb. 2.

Watch Demi Lovato's 'Nightingale'

Click Here to Preview/Purchase Rihanna's 'FourFiveSeconds'