Kozak has netted twice for his new club since arriving from Lazio.
"It must have been difficult coming in knowing he has to compete with Christian (Benteke) - one of the best strikers in the world," Agbonlahor said in the Birmingham Mail.
"He has come in, scored and has been a handful.
"It was good for Libor to score at Villa Park against Cardiff.
"He battles on during games and he got his reward for working hard. He is quiet and keeps himself to himself but he enjoys his football.
"He tries his hardest and that's what the manager wants, people who are going to give 100 per cent."
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