"Grenade" supplanted "Firework" two weeks ago, only to have Perry's track reclaim the chart's lead spot for a fourth cumulative frame on last week's ranking. It is the first time two songs have alternated holds at No. 1 over four weeks since "Live Your Life" by T.I. featuring Rihanna traded spots with Beyonce's "Single Ladies (Put a Ring On It)" in December 2008. Mars' track sits atop Digital Songs for a fourth straight week with 275,000 downloads (down 35%), according to Nielsen SoundScan, as the post-holiday glow has finally worn off the digital download market with total sales dipping by 29% this week.
Threatening the reign of Mars' "Grenade" or the return of Perry's "Firework" to No. 1 next week will be the arrival of Britney Spears' "Hold It Against Me," which was released near-simultaneously at radio (Jan. 10) and exclusively at iTunes (Jan. 11). With airplay off to a blazing start and track sales set to exceed 400,000 according to industry sources, a second No. 1 debut for the pop starlet is likely. She previously started at the summit with "3" on the chart dated October 24, 2009.