Northern Ireland international Stuart Elliott won the game for Rovers after Jose Enrique showed once again he is lacking in strength, vision and Premiership ability.
Keegan has made it plain and clear that we need a left-back, and if anyone had any doubts, Saturday's none-event in Yorkshire showed where the main problem lies.
And more worryingly, the scoreline could have been heavier had it not been for young Dutch keeper Tim Krul who came off the bench to pull off some fine saves.
United handed a chance to on trial Metz defender Sebastien Bassong and Keegan made Geremi skipper.
Former Toon youngster Lewis Guy had Donny's best chance of the first half when after his ex-United colleague James Coppinger swung in a corner he latched on to Gareth Taylor's flick - only to fire over from close range with 10 minutes left of the first period.
After the break Donny new boy Tomi Ameobi entered the field to do battle with his older brother Shola.
The second half burst into life on 51 minutes when a great run from Charles N'Zogbia down the left resulted in a left foot snapshot that flashed wide of Ben Smith's goal.
Keegan brought on Tim Krul for Steve Harper on the hour and the 'keeper was the only 'plus' in a poor team performance.
He was called into action within seconds when Elliott tested him from distance and the Dutch youth international turned the ball round the post.
Shola Ameobi set up Alan Smith but the England international put his header wide.
Geremi was involved in most of Newcastle's threatening moves, although nothing came from any of them.
Shola Ameobi did the hard work when he skipped through the Donny defence but his powerful low effort went straight at the keeper.
N'Zogbia was the star of the day, with little competition from anyone (apart from Krul) and his shot into the side netting was the closest United came to scoring.
Krul produced another great save with nine minutes left on the clock when Elliott's powerful free-kick from range was parried away by the Dutchman.
But Bassong and Jose Enrique got in a mix up, bumping into each other after Ben Smith's long ball, and Elliott scored with three minutes to go.
NEWCASTLE UNITED: Harper (Krul 57), Taylor, Bassong, Cacapa (Edgar 64), Enrique, Geremi (Tozer 78), Guthrie, N'Zogbia, Duff, Ameobi, Smith.
Subs: Morris, Tozer, Danquah, Doninger ,Donaldson, Godsmark.
Ref: Rob Shoebridge (Derbyshire)