According to Sportitalia and MilanNews.it, the clubs are in intensive negotiations and it is progressing rapidly.
This would be a paid one-season loan with Atalanta covering his annual salary, plus an option to buy at the end of the campaign.
There are numerous clubs interested in signing De Ketelaere, but the Rossoneri must avoid losing him for less than the €35.5m they paid to Club Brugge only a year ago.
To make matters worse, Club Brugge also retain a 12 per cent cut of the future sell-on fee, which cuts it down even more.
Real Sociedad were the latest to be linked with the Belgian, after Aston Villa, RC Lens, PSV Eindhoven and RB Leipzig.
Atalanta would also be preferred because it’d give De Ketelaere the opportunity to play regularly in Serie A and prove what he can do with more support and confidence.