Norway striker Haaland has been a revelation since moving to the Bundesliga in January, continuing the prolific form he enjoyed at Salzburg to score 16 goals in 18 appearances across all competitions for BVB.
It means a lack of specialist cover only heightens Lucien Favre's dependence upon the 20-year-old Haaland, but Dortmund's sporting director Michael Zorc suggested weaknesses are in other areas ahead of their latest attempt to haul in Bayern Munich.
"We didn't score too few goals last season," Zorc told Kicker, with Favre's men scoring 84 times in 34 matches as they finished the 2019-20 campaign 13 points shy of Bayern.
Zorc feels Favre's fluid attacking approach, which has seen the likes of Jadon Sancho, Thorgan Hazard and teenager Giovanni Reyna occupy central attacking roles at various points, means there is no need to add another traditional striker to the mix.
"In this sense, there is no classic nine anymore," he said.
Haaland's reported release clause of €75million could yet nudge some of Europe's heavyweight clubs into action, although Sancho's future is currently a subject of greater speculation.
The England winger has been linked with a return to his homeland, with Manchester United reported to be the frontrunners for his signature.
Dortmund have already secured the services of Thomas Meunier and English teenager Jude Bellingham, and Zorc feels their business might be done with regards to incomings – a situation that would change if Sancho departs.
"If Jadon leaves, there is a need for action," he added.