Kozak believes that despite scoring his first goal for Villa last weekend, his form has been "far from ideal", but Lambert has reassured the Czech striker that he is under no pressure to hit the ground running.
The 44-year-old told the Birmingham Mail: "It was the same with Christian when he first came. He scored against Swansea, it took him a few weeks to get a feel of it and to get going and the rest, as they say, is history with him.
"It wasn't just as if Christian came in, hit the ground running and all of a sudden, he became this player that everybody speaks about. It took him a little while to get going. With Kozak coming in, it's virtually the same kind of impact. He scored after coming on.
"If he plays today, he's had the Norwich game to bed himself in and the Spurs game the other night. He's only been here for a few weeks, he's not been here that long at all."
The former Lazio frontman was the top scorer in the Europa League last season.