It was the Black Eyed Peas' Big Day Out shows in Auckland and Australia during 2001 - when they performed alongside Coldplay and Limp Bizkit - where rapper Will.i.am found out what it takes to rule the stage.
"Those festivals taught me how to hold my own in front of rock fans," he says. The mega-selling musician, producer and entrepreneur is back Downunder this week, having appeared on The Voice Australia and to play the Hallenstein Brothers' Ultimate After Party bash in Auckland tonight.
Since the Big Day Out, he has watched the Black Eyed Peas become one of the most successful pop groups of the decade, winning six Grammys and selling tens of millions of albums and downloads. They rank alongside Madonna and Beyonce as acts to be given a lucrative Super Bowl half-time slot, while I Gotta Feeling is the most downloaded song on iTunes.
Eyebrows were raised when Will.i.am put the group on hiatus two years ago, a move he says was important to test his creative powers.
His first solo album, #willpower, features collaborations with Justin Bieber, Miley Cyrus and Britney Spears, and yet the 38-year-old singer admits to nerves over its release.
"To have global success with the Peas and then step outside of that as an individual - it's kind of hard and scary," he says. "It's worse than starting from scratch because at least if you start from scratch and fail nobody ever knew you."
If anything, Will.i.am's profile has skyrocketed after a stint as a mentor on Britain's The Voice and through his interaction on social media.
He famously tweeted his 6.8 million followers while carrying the Olympic Torch through England, and was the first artist to stream a song from the surface of Mars.
He's invented a camera attachment for iPhones and become Intel's director of creative innovation.
"Technology is something that I'm just thrilled about," he says.
"It inspires me in the way music did when I was 15 years old, when I woke up wanting to write songs, or wanting to rehearse a dance or make some beats.
"Now here I am 20 years later and I wake up thinking about devices. I wake up wanting to write code. I wake up thinking about what tomorrow is going to be like."
Where: Hallenstein Brothers' Ultimate After Party, tonight
New album: #willpower, out now.