While the top of the Pop chart will remain mostly unchanged, there are two tracks joining the Top 10 this week that will soon be battling for #1— Justin Bieber's "What Do You Mean?" (RBMG/Def Jam), which vaults up to #9 and Taylor Swift's "Wildest Dreams" (Big Machine/Republic). This is about to get real, because Bieber has a comeback in progress, while Swift is on a quest to beat Katy Perry's Teenage Dream record for having the most #1 singles from one album. "Wildest Dreams" would be her fourth if it hits the top—she needs five in order to tie Perry. Meanwhile Macklemore & Ryan Lewis' "Downtown" (Macklemore/Warner Bros.) and Nick Jonas' "Levels" (Safehouse/Island) take significant jumps inside the Top 20. Charting this week will be RCA's Nicky Jam & Enrique Iglesias' "El Perdon (Forgiveness)."