McInnes and assistant Tony Docherty worked with Watson during their time at Tannadice and jumped to run the rule over the 25-year-old.
Watson spent the second half of last season on loan at Hibs but injury prevented him from taking part in any of the Edinburgh club's pre-season matches.
Now Hibs boss Alan Stubbs has dropped his interest in the player, and while some sources suggest McInnes is allowing Watson to train at Pittodrie to regain his fitness, Stubbs is convinced the defender can impress the Dons staff.
Stubbs told the Edinburgh Evening News: “Keith was here, he came into training but he had an injury which kept him out for a bit. As a result, we have decided to move on. Keith had an opportunity to go to Aberdeen so we have allowed him to go and try to pursue something there.”
Source: Edinburgh Evening News