With Germany up next for Brazil in the semi-finals, Hamann has questioned whether they will be able to cope with the loss of the 22-year-old.
"Brazil now need someone to stand up, shoulder the responsibility and fill in for him," he told FIFA.com. "I think Hulk is their best bet, but they'll miss Neymar's moments of magic.
"Now we'll see whether or not their attack is still strong enough to cause Germany some problems."
Germany and Brazil go head to head in the last four of the World Cup in Belo Horizonte on Tuesday evening.