Before the 2-0 home defeat there was speculation that the Belgium international would be back in the Villa starting line-up after a month out with a hip injury.
However, he was only among the subs and came on for the final half an hour, replacing Libor Kozak, as Villa attempted to get back into the game in the second half.
Lambert has defended not starting the star forward and insisted he was not fit enough to play the full 90 minutes.
The Villa boss said: "Christian has trained four days in a month. It's unfair to expect him to fit right in from the beginning.
"He has only trained a couple of days with us and the same with Belgium. It was not enough to throw him into that magnitude of game. Plus I am happy with Libor. It was never an option.
"But he got half-an-hour and it will do him the world of good."