"I am not envious or jealous of the other players," the 28-year-old, who has four goals in 13 appearances since joining on a free from Bayer Leverkusen, told liverpoolfc.tv.
"I have a very good relationship with the other strikers and it is up to the manager to decide who plays in any particular game.
"It's not about individuals, it's about the team, but Dirk is a very good striker.
"Sometimes strikers make mistakes, sometimes defenders do; sometimes teams score, sometimes they hit the post. But Dirk is a very good player and I am sure we'll see him back to his best in the next few weeks.
"He participates as a member of the team so well, he works so hard to defend. He is an excellent player."