In her first face-off after taking the Pop Clash title from Britney Spears, Lady Gaga proved she's a force to be reckoned with! Mother Monster went head-to-head with rising star Lorde, and her R. Kelly collabo took 90 percent of the votes! This week, 'Do What U Want' is up against Christina Perri's 'Human.' Which song should win? It's up to you to decide!

The Lady Gaga/R. Kelly pairing was as surprising as it is awesome! 'Do What U Want' showcases the best both singers have to offer. We love that Gaga is radiating confidence with this song, and R's sultry crooning makes this provocative track an instant fave.

Christina Perri takes an almost-ethereal tone with 'Human.' The power ballad starts off lightly, then builds as she proclaims that she's only human. Like Gaga, Christina also exudes self-assurance. The track emphasizes that she can take on any challenge, but at the end of the day, she's still capable of failure.

Who should win this week's Pop Clash? You can vote for Lady Gaga or Christina Perri once an hour until the polls close at 3PM on Dec. 23.

Listen to Lady Gaga, 'Do What U Want' Feat. R. Kelly Video

Watch the Christina Perri 'Human' Video