Arsenal manager Mikel Arteta and director of football Edu disagreed over a key summer signing.
The defensive midfielder arrived from Atletico Madrid on deadline day.
But the source claims it was Lyon's Houssem Aouar that Arteta would have preferred.
He believed the team needed more creativity from midfield.
And it was evident as they lost 1-0 to Leicester City after a toothless home performance.
The Gunners continue to be linked with a January move for Aouar.