NEW YORK - Bruno Mars ended Katy Perry's three-week reign on Billboard's Hot 100 singles chart on Wednesday, rising one place to the top with "Grenade," his second No. 1 hit as a lead artist.

He previously led the chart for four weeks in the fall with "Just the Way You Are," which was off four places to No. 10 on the latest chart, and was the featured artist on B.o.B's May chart-topper "Nothin' On You."

"Grenade" sold a near-record 559,000 downloads (up 164%), according to Nielsen SoundScan, as the unwrapping of MP3 players and the traditional post-Christmas gift card redemption surge resulted in a 108% increase in overall download sales for the week. Perry's "Firework" followed with 509,000 downloads, slipping to No. 2 on the Hot 100.

Those sums move "Grenade" and "Firework" into the Nos. 3 and 4 slots, respectively, among the biggest single-week sales frames behind Flo Rida's "Right Round" (636,000) and Ke$ha's "TiK ToK" (610,000), both in 2009.

Back to the Hot 100, the songs that ranked from Nos. 3-5 were all former No. 1s. Ke$ha's "We R Who We R" rebounded two places to No. 3; "What's My Name?" by Rihanna featuring Drake slipped one to No. 4; and Pink's "Raise Your Glass" was off one to No. 5.

Rapper Wiz Khalifa's first charting effort, "Black and Yellow," jumped six places to No. 6. Enrique Iglesias was also up six, to No. 7, with "Tonight (I'm Lovin' You)."

Trey Songz's "Bottoms Up," featuring Nicki Minaj, hasn't had its fill of the top 10, as it rebounded three places to No. 8. The song has climbed into the top 10 three times during its chart run, spending a cumulative nine weeks in the region. The Black Eyed Peas fell one to No. 9 with "The Time (Dirty Bit)."

The chart's top debut belonged to comedy troupe the Lonely Island, which entered at No. 30 with "I Just Had Sex," featuring Akon. The song was featured in a skit on the December 18 episode of "Saturday Night Live" (Lonely Island includes "SNL" cast member Andy Samberg).