The Black Eyed Peas man talks about the "bonding" the pair enjoyed in the run up to teaming up together.
Will.i.am Stops Justin Timberlake From Claiming Vodafone Big Top 40 Number One
The Black Eyed Peas star's track with Britney Spears spends its third week in a row at the top of the chart.
Will.i.am and Britney Spears have held onto the number one spot on the Vodafone Big Top 40, despite a challenge from Justin Timberlake's comeback 'Suit & Tie'.
The duo's collaboration 'Scream & Shout' has topped the countdown for the past three weeks.
Justin Timberlake made his big return to music on Monday morning (14th January), unveiling the Jay-Z featuring track on iTunes.
It marks the first song from his forthcoming album 'The 20/20 Experience', which is the former N*Sync star's first album since 2006.
Elsewhere on this week's chart, Bingo Players were a new entry at number eight with 'Get Up (Rattle)'.
The Black Eyed Peas man praises the Royal at a New York fundraiser dinner this week.
Check out a battle of the moves from PSY's 'Gentleman' and Will.i.am's '#thatPOWER'.
The star says his $900,000 car was a project aimed at inspiring young people to go into scientific subjects.