The Dublin winger still has half of his contract left to run, so either KK listens to offers in the summer, or he will have the player on his books - like it or not.
But the Newcastle manager said he is happy enough with the winger, despite suggesting he is looking abroad for another player to play in Duff's position.
Keegan: "Damien Duff is a key player. I keep telling him that every day.
"I don't tell him that because I am trying to keep him sweet. I tell him that because I honestly feel he has a major role to play."
"We've not only got a good team of players at the minute, we've also got a good squad around it."
"What you have to have in your squad is the ability to change things at all times.
"We've got that with someone like Damien Duff he's on fire at the moment.
"He's champing at the bit to get back in the team and then it'll be James Milner in the next ten days or so wanting to get back in as well.
"You'll see now when Duff, Milner and Smith come back in and they will they'll be coming back into a side which has some confidence. That can make a major difference to how they play as well."