Ariana

"PROBLEM" SOLVED: Republic's Ariana Grande is off to a roaring start with single "Problem" featuring Iggy Azalea. The track, which the diva premiered at the Radio Disney Music Awards over the weekend (see above) debuted yesterday at iTunes and immediately flew to #1; since then it's been outselling its nearest competitor on the singles chart by a factor of three or four to one. This week's Wildcard pick, produced by Max Martin and Savan Kotecha, impacted and is Most Added at both Pop and Rhythm radio this week. Big props to Monte Lipman, Charlie Walk and the rest of Team Republic. (4/29p)