He tells Billboard.com, "I've got this one record I've been holding for 10 months that everyone has tried to buy, but I stayed with Britney on it. I guarantee it will shake up the world.
"It's uptempo, out of control... It's wowzers, produced by me and Bloodshy. I can't give the title yet, but the record is done and definitely what people want to hear from her."
And Garrett knows what he's talking about - he shared the Songwriter of The Year honour at the BMI Awards in May.