He could be called upon to play there again against Southampton on New Year's Day if Jordan's swollen ankle doesn't heal and Ben Thatcher fails to prove his fitness after 10 games out, which presents no problems for Keegan.
"I thought he was one of the bright sparks on Tuesday against West Brom," Keegan told the M.E.N.
"He came on and he did excellently in a position in which I have never seen him play before."
The City boss has been impressed with Onuoha's progress this term and has predicted a long future for him at City.
"Nedum has proved to me over the past six months that he is ready," he added. "When he does get his chance and gets into the side in his best position, which is as a central defender, he is going to play a lot of games - once he gets that shirt he will be hard to shift.
"That's because he has got everything you need. He has got pace and strength, and he knows what forwards are thinking as he reads the game
well.
"Everything we have asked of him so far he has taken in his stride. He is a very bright boy, on and off the pitch. We know he will learn quickly because he wants to get to the next level."