Wolfsburg are currently the only other club rivalling Tottenham for Vincent Janssen, Sky sources understand.
Sky Sports News HQ reported last week that the Dutch international striker had been given permission by current club AZ Alkmaar to speak to Spurs, and he spent a day in London listening to Mauricio Pochettino's vision.
It is understood that Wolfsburg are the only other club that Alkmaar have given permission to speak to Janssen at this stage.
Sky sources also understand there has still not been any contact from Spurs to discuss a transfer fee with the Eredivisie club.
Sky Sports News HQ have previously reported that Tottenham are very interested in Marseille's Belgium international striker Michy Batshuayi.
But Spurs are unsure about paying the French club's asking price - understood to be around £32m - and are aware of strong interest from Borussia Dortmund and Juventus.