The former Tottenham defender is available at a bargain price and wants to return to the Premier League from Germany.
N'Zogbia admits he feels like a fish out of water in defence, but he has put in some superb performances on the counter attack when playing at St James' Park.
But it seems he struggles playing the out-and-out defensive game when United get pushed back, particularly on their travels.
He struggled against Man Utd, but KK knows his options are limited, and he prefered the pace of N'Zogbia to Jose Enrique's unpredictable foem.
Keegan is desperate for a left-back and has homed in on 6ft 3in Atouba, 26, after Toon's transfer negotiators failed to land Steven Warnock from Blackburn.
Rovers would want well over £6million and that is well wide of KK's bid of £2.25m two weeks ago.
Rovers will make a stand, even though rumours from Ewood Park suggest Warnock would "love" a move to St James' Park.