After months of hype and warring words, Epic Games is about to get its day in court with Apple.
The trial begins on Monday - and is one of the most important in Apple's history.
Apple boss Tim Cook will be giving evidence, the first time he's given testimony at a trial.
At stake is the future of the App Store and the amount it charges developers - a wildly lucrative money spinner for the company.
In August last year, Epic Games laid a trap for Apple.
Its hit game Fortnite implemented its own in-app payment - bypassing Apple's 30% charges.
Apple promptly kicked Epic Games off the App Store.
But Epic Games was waiting for just that.
It slapped Apple with a 65-page lawsuit - and had even prepared a high production video, a spoof of Apple's iconic 1984 advert for the Apple Mac.
Epic Games has for years claimed the charges imposed on it by Apple are extortionate.
Their argument is simple: that Apple's control over the App Store is anti-competitive.
It believes that developers should be able to make apps for smartphones without having to pay large sums to Apple (and to Google for Google Play purchases).
Spotify, Match and Tile are just a few of the many companies that have also claimed Apple's charges are unfair.
Apple is estimated to have made hundreds of millions of dollars from Fortnite alone in charges.