The 22-year-old has been a target for Spurs all summer, with the London club looking to bolster their attacking options to lessen the load on Harry Kane.
With AZ standing firm on the fee, having increased their original asking price following interest from other parties, Press Association Sport understands Spurs are ready to pay £17million for the man who finished as the Eredivisie's top goalscorer last season with 27 goals.
Janssen was given permission by AZ to travel to London last month and he visited Tottenham's training ground, met with head coach Mauricio Pochettino and is believed to have all-but agreed personal terms with the side who finished third in the Premier League last season.
Having returned to London on Sunday night, Janssen could officially be announced as early as Monday afternoon if his medical and the final contract talks run smoothly, having confirmed last week he always had his heart set on White Hart Lane.
Quoted by Algemeen Dagblad, in an online article including photos of the player apparently saying his goodbyes at the training ground, Janssen confirmed: ''I won't train with AZ any more
The clubs are now really close to an agreement
I will go home and wait for the phone call to go.
''I am glad that it is almost complete
For me it was clear from the beginning that I wanted to go to Spurs."
Although he is likely to play second fiddle to Kane, getting most of his chances in cup competitions, Janssen - who has had a summer off after Holland failed to reach the finals of Euro 2016 - could start the new campaign as Tottenham's main striker if Kane is eased back in following his England exploits.
The deal will be the largest-ever fee received for a player by AZ - who will double their previous record set when they sold Jozy Altidore to Sunderland in 2013.
Source : PA
Source: PA