And in the aftermath of yesterday's fantastic win, the City boss spoke of his delight with the ex-Real pair - in particular his hopes for Anelka and the debut performance from Macca.
"I think eventually we will have the best striker in the world at Manchester City," believes Keegan.
"People will laugh at that but there are still things that he can do better. What he is good at he is as good as anyone in the world at. He has a change of pace and quick change of direction but he will become a better finisher than he is at the moment.
"You have to think what he will be like with another three years of experience behind him," said the City supremo.
"At present he scores maybe one in every three chances but I feel that will come down to one in two and that's when he will end up leading the goal-scoring charts - though he is pretty much up there this year."
"He is always going to score if we give him some ammunition," reckons Keegan - and the Frenchman certainly proved that yesterday.
Indeed, with the creative talent of McManaman at the Blues disposal, there was plenty of ammunition supplied.
"If I had to pick the Man of the Match it would be Nicolas Anelka as he got a hat-trick, but I thought Steve McManaman had a great debut," admitted Keegan.
"His fitness levels were a credit to him, his willingness to work for the team and chase lost causes and his inventiveness was good."
"Anyone who doubts whether he can play in the Premiership had their answers in the second forty five minutes. He was just about at the hub of everything we did."