Diouf signed for Hannover from Manchester United in 2012 following a three-year spell at Old Trafford.
The Senegal international failed to establish himself with the Premier League club and also endured relatively unsuccessful loan spells at Molde - who he had initially left to join United - and Blackburn Rovers.
However, the 25-year-old has since made a big impact at the AWD-Arena, and Stoke are thought to be eager to bring Diouf back to England.
The Britannia Stadium club were reportedly close to sealing a deal for Diouf's services, but Dufner revealed that the forward has not yet held any talks with prospective new manager Mark Hughes.
"Mame told me he hadn't yet spoken to Stoke's coach," Dufner told Kicker.
A potential agreement for Diouf also appears to hinge on Hannover's ability to find a replacement to fill the void in attack.
"We have no substitute," Dufner added.
Diouf was part of the Hannover team that eased to 2-0 win over nine-man Wolfsburg in their opening game of the Bundesliga season on Saturday.
Club president Martin Kind is eager for Diouf to remain with his side, but remains unsure over the player's future.
"He is a good fit for Hannover and has shown how important he is," Kind said.
"We can decide, which is the important thing. We want to play the season with him and stay with us as long as possible.
"I have learned that you can't rule anything out, but I'm relatively sure (he will stay at Hannover)."
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