Speaking ahead of the Klassiker on Tuesday, Flick said Haaland needed much more time to be compared with the prolific Pole.
"It is [Haaland's] first season, so comparing him now is too early," Flick told reporters.
"Robert has always been at a world-class level in recent years. But Haaland is a huge talent.
"He is a young player, but he has a huge pull towards the goal. He just wants to finish.
"He has a brilliant dynamic. He is greedy, is an enormous size but is still agile. But we don't just have to watch out for him [on Tuesday]."