The singer will feature on the Black Eyed Peas rapper's upcoming solo album #willpower on a track rumoured to be titled 'Sexy Sexy'.
"@britneyspears OMG...your lookin fit & hot...can't wait to shoot the video to our song...your fans are ganna love it..." will.i.am tweeted yesterday (August 30).
Asked if he prefers his new single with Spears over their previous collaboration 'Big Fat Bass', he said: "I like the new song I did with @britneyspears 900,000,000,000,000,000x's more than BFB...and I loved BFB...#crazyfire"
will.i.am's new solo album is due out on October 15 and is expected to feature collaborations with Nicole Scherzinger, Chris Brown, LMFAO and Rihanna.
Listen to Britney Spears and will.i.am's 'Big Fat Bass' below: