According to Myspace, the opening track of Britney Spears’ upcoming album Femme Fatale has leaked online. “Till the World Ends” is written by Ke$ha and produced by Max Martin and Dr. Luke. Slated for release later this March, Spears’ latest set will include three tracks from the Swedish songwriter/producer Shellback.

Originally released in November 2010, Flo Rida’s “Turn Around (5, 4, 3, 2, 1)” makes its official debut on the Swedish singles tally this week at No.54. The Haiti-American rapper and singer Flo Rida, née Tramar Tillard (1979), got his breakthrough in 2007 with the US No.1 “Low” (feat. T-Pain). He has released three studio albums to date and was the first one to break Ke$ha on “Right Round” – a No.1 hit in 2009.

Avril Lavigne will issue her fourth album ‘Goodbye Lullaby’ in March. The set will include the first single “What the Hell” and reunite the Canadian pop star with Swedish producer Max Martin.

Bruno Mars vaults to No.1 on this week’s Billboard Hot 100 with “Grenade.”