Manchester United and Arsenal clashes are never short on storylines, but there is one developing which in a few years could top the lot.
Arsenal youngster Chris Willock played alongside several first team stars in pre-season, while his brother Matty Willock is pushing for a place in Manchester United's under-21 side.
The prospect of them facing off against each other in the Premier League is one day a possibility, but it could so easily have been alongside each other, with Matty Willock at Arsenal previously before being released two years ago.
Manchester United snapped him up, and he is hoping to show the Gunners they made a mistake, despite admitting he was gutted to leave.
He told Inside United: "I was a schoolboy at Arsenal but was released at 15 so I had trials at a few clubs, including Reading and Sunderland. I ended up signing for United.
"It was a bit disappointing when I left Arsenal but it worked out well."
Willock is now 18-years-old and has switched from being a winger to a central midfielder.
He is training with United's under-21 side and patiently waiting to make his breakthrough as a regular, having made the one appearance to date.
"You can see what level you are at and what you need to improve on. It enables you to see you’re getting close to the level required if you can compete with Premier League players."
He even has another younger brother at Arsenal, Joe Willock, part of the under-16 side.
The last player to leave Arsenal for United, more directly, was Robin van Persie, while Danny Welbeck moved in the opposite direction only three months ago.
The most well known brothers to play against each other in recent years are Kevin Prince-Boateng and Jerome Boateng, who not only play for rivals Schalke and Bayern Munich, but for different international teams with Ghana and Germany respectively.