Haaland has scored 33 goals and provided eight assists in just 31 games at Westfalenstadion this season, making him one of the most wanted players in the game.
Elite clubs in Europe revolve around the 20-year-old ahead of the summer transfer window, with Liverpool being one of the numbers strongly linked to interest in the Norway international.
However, Sammer believes Haaland should be patient and continue to develop at BVB – citing Ousmane Dembele’s stint at Barcelona in 2017 as an example of what can go wrong.
“I would recommend Erling to also see the value of Borussia Dortmund,” Sammer told Sport Bild. “The club has given him a lot. From there he can only go to a handful of clubs. When Erling takes the next step, he has to be the finished, perfect product. He’s very, very good. ”
“He needs to improve some details. Robert [Lewandowski] was full when he left for Bayern [Munich on a free transfer in 2014]. It was clear: he went straight into the starting lineup. But as a counterexample, Ousmane Dembele may have left a moment too early for Barcelona. Erling is far in his development, but he is not complete.
Sammer’s comments come just days after Haaland revealed that for a club to be able to secure their services, they “have to” show they want to.
When asked what qualities a club must have in order for him to sign for them, Haaland responded with an understandable response: “They must want me. ”
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Manchester United and Man City are also said to be interested in the talisman, while Real Madrid and Barcelona have also been mentioned as potential contenders and agent Mino Raiola is expected to present a whole host of offers when the market opens for the end of this season.
However, in the same interview, Haaland – who is on an international mission – decided to pour cold water on the growing speculation surrounding his future by pointing out that he still had several years left on his contract at Dortmund.
He added: “I still have a three-year contract, that doesn’t worry me. ”
Meanwhile, Sammer was also asked if his former employers Bayern Munich could eliminate Haaland – as they have done with Robert Lewandowski in the past.
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“It won’t happen today or tomorrow because Bayern already have Robert Lewandowski,” he replied on Bayern’s links.
“Robert is absolutely world class, Erling is on his way. He has hunger in him. I’ve never seen anything like it in terms of stats and hunger for goals at this age. ”