British pop-R&B breakthrough artist Jessie J scored her first U.K. No. 1 single yesterday as "Price Tag" (Lava/Universal Island), featuring B.o.B, debuted at the top. Adele's "21" (XL Recordings) started a second week atop the album chart.

Jessie J will be the recipient of the Critics' Choice title at the BRIT Awards in London Feb. 15, and the single success is an early vindication of the new cross-industry "on air, on sale" initiative, under which labels are committing to make more tracks available for official download around the same time they go to radio. Her debut hit "Do It Like A Dude," which reached No. 2 last month, has sales in excess of 300,000 units, according to the Official Charts Company, and is still in the top 10 at No. 7.

Bruno Mars' former chart-topper "Grenade" (Elektra/Atlantic/Warner Music) held at No. 2 as Ke$ha, last week's debutante at No. 1 with "We R Who We R" (RCA/Sony Music Entertainment), fell to No. 3. Adele's "Rolling In The Deep" dipped 3-4 as "Tonight" (Interscope/Universal) by Enrique Iglesias featuring Ludacris debuted at No. 5.

"Higher" (4th & Broadway/Universal Island) by Taio Cruz featuring Travie McCoy and Kylie Minogue jumped 17-8 and Chris Brown's "Yeah x3" (Jive/Sony Music Entertainment) 10-9.

Adele's "21," which had sold a hefty 208,000 in its debut week, added another 135,000 sales last week to keep the album crown. London production duo Chase & Status debuted at No. 2 with "No More Idols" (Mercury/Universal), which includes the current hit "Blind Faith" featuring Liam Bailey, itself down 5-10 in its second week.

There was another posthumous album success for American vocalist Eva Cassidy, whose "Simply Eva" (Blix Street) debuted at No. 6. It's Cassidy's fifth U.K. top ten album, all achieved since her death in 1996, three of which hit No. 1. There were also top 20 debuts for London MC Skepta's "Doin' It Again" (All Around The World/Universal) at No. 19 and Rhino/Warner Music's TV-advertised "Love Songs" compilation by Roberta Flack.