"Nicolas Anelka is a quality player and I know he didn't want to leave Liverpool," Keegan said after the 2-1 victory.
"He wanted to stay but Gerard Houllier had a difficult decision to make and had other options.
"Last summer Nicolas wanted to wait until Liverpool's option on him had expired before he talked to us. Now he's come back to Anfield and done what all good goalscorers do, score important goals."
Keegan also singled out the performance of keeper Peter Schmeichel after his heroics kept City in the game: "Peter is the best goalkeeper the Premiership has ever seen, he's impossible to replace like for like and can still hack it with the best.
"He's not retiring because he's not good enough anymore, he's going because he has other things he wants to do."
LIVERPOOL MATCH REPORT