Vlaar was delighted for Benteke after his performance in victory over Sunderland.
He said: "He scares opponents. You can see that in games. When Brad Guzan kicks a long ball a lot of time they don't even bother challenging him because he's so strong so he takes it on his chest.
"A lot of strikers in England are like that. But with his height and his body, he's very strong.
"And he's still growing.
"He also had to get used to the way of playing in England so he also learned to defend himself, keeping the ball and things like that, so he has definitely become a stronger player.
"I see him in the gym. He still does strength work. Mind you, he doesn't lift as much as me..."