Jeremy Scott had to dress Katy Perry like a "Russian nesting doll" for the Super Bowl 2015.
The 40-year-old fashion designer - who created four iconic looks for the 'I Kissed A Girl' hitmaker's half time performance at the annual event held at the University of Phoenix Stadium in Arizona last night (01.01.15) - has revealed he worked out a system of layering the eye-catching outfits on top of each other to minimise her changing time during the hotly-anticipated 12-minute set.
He said: "Making it manageable to get her into four looks in about 10 minutes without her ever leaving the stage has been the trickiest part.
"The concept is kind of like a Russian nesting doll where you have things on top of things, and then you put something else on before you take something else off. It's been more of a math and science lesson about layering, how to hide and to have her have big reveals."
Katy, 30, wowed the audience in a flame-patterned mini-dress during the performance of her hit 'Roar' and sported a black embellished hooded sweatshirt as she sang a trio of tracks with Missy Elliot.
She also donned a beach-ball-inspired sundress during 'Teenage Dream' and 'California Gurls', before changing into a star spangled silver outfit for her 'Firework' finale.
The creative director of Moschino credited the brunette beauty for "rising to the occasion" after he convinced her to add a fourth look to her set.
He said: "I don't think anyone has taken on four costume changes for a Super Bowl performance ever. I really have to give it to Katy for rising to the occasion. We were originally only going to do three and I actually encouraged her to do a fourth."
Jeremy went on to gush over the singer - with whom he has had a "wonderful joyful" friendship and partnership.
He told WWD: "Before her first album came out, she came up to me at an event in LA and told me that I was her favourite designer. She said that she was a singer and that one day she was going to have an album out, and she hoped that one day she would be able to wear my clothes.
"She's more than achieved one of her dreams. That was one of her dreams. We've been doing things together ever since. So we've had a wonderful joyful friendship and creative partnership."