Congratulations to Katy Perry, whose spooky Prism track (and GRAMMY performance song) "Dark Horse" is now at no.1 on Billboard's Hot 100 chart. It replaces Pitbull ft. Ke$ha's long-term spot at the top of the list, sending the party-ready jam to the number 2 slot. Looks like Perry's appearance at the 2014 GRAMMYs might have helped her climb up the chart. Sitting tight at spot number 3 on the Hot 100 countdown is OneRepublic's Native track "Counting Stars", while indie duo A Great Big World are securing the #4 slot with their Christina Aguilera-assisted hit "Say Something". Coming up in fifth place is Eminem ft. Rihanna's "The Monster", who used to sit at no.1 before Pitbull took over. Based on how popular Katy Perry's witchy anthem currently is, we wouldn't be surprise if it stayed at the no.1 position well into next week.