Haaland hasn't stopped scoring since his arrival at the German side from Austrian outfit RB Salzburg in January.
He has been the proposed target of many European giants including Manchester United, Real Madrid and Liverpool, and the German stopper reckons that we are entering the era of Erling over the next few years.
"[He is an] Incredible goalscorer and hard worker," Hummels said to CBS Sports. "I think that is something the people do not know because they see the work only on Tuesday, Wednesday and Saturday.
"They just see it on the pitch, but the work behind it is what makes him so good because he is working on himself. He knows what he can do, what his strengths are, but he knows his weaknesses as well and he is working on them.
"I am 100% convinced Erling will be one of the greatest goalscorers in the next 15 years, no question about it."
Haaland has scored 24 goals in 27 games for Dortmund in all competitions. The German side bought Haaland for an estimated fee of £20m earlier this year.