"For us, he is worth his weight in gold because he can carry the team along," Dortmund sports director Michael Zorc said of Haaland.
"Every minute, he shows that he wants to be successful."
The 20-year-old showcased his lethal finishing with two goals in Tuesday's 3-0 win over Brugge.
He has hit 17 goals in 13 games for Dortmund this season, including netting 10 times in seven Bundesliga games, and continues to shine in the Champions League.
He is the first to score 16 goals in his opening 12 European games, breaking the record held by Ruud van Nistelrooy and Roberto Soldado, who both needed 19 games to reach the 15-goal milestone.
Having scored eight times in six group stage games for Red Bull Salzburg last season, Haaland has netted another eight in six Champions League games for Dortmund since his January transfer.
Not even the likes of Messi or Ronaldo scored so many Champions League goals at the start of their illustrious careers.
"Erling is a fantastic player," said England winger Jadon Sancho, who hit the net with a superb free-kick on Tuesday.
"I am happy to play with him - he works hard every day on and off the pitch."
Having also scored four goals in Saturday's 5-2 rout of Hertha Berlin, Haaland's form has taken Dortmund to the verge of the last 16 in Europe.
A home win against Lazio next Wednesday will put Dortmund in the Champions League's knock-out stages.
With the games coming thick and fast, Dortmund coach Lucien Favre warns that the 1.94m Haaland needs protecting.
"He's still growing, sometimes he has a problem with his knee. If we overdo it, it could work against us afterwards."
Haaland "always wants to play -- but that's my problem," Favre added.
Dortmund are one point behind European champions Bayern Munich in the Bundesliga.
"We are achieving good results and playing well, there is a lightness in the way we are playing," said former captain and current player licence director Sebastian Kehl.
"We want to have a run up until Christmas. We can achieve a lot," Kehl added with Dortmund still facing eight games in the coming four weeks.