Rehhagel hopes to avoid relegation
Hertha failed to build on their 3-1 win over Mainz last weekend as they slipped to their ninth league defeat in 11 games in 2012.
The capital club are now four points adrift of safety, but Rehhagel is still hopeful of staying up. "We thought that we had turned things around, but we are not that far away either," he said.
"As the saying goes 'it's not all over until the fat lady sings', and Hertha's fat lady has not started singing yet. We will try all we can to stay up."
The size of the defeat will do little for Hertha's goal difference, coming just a fortnight after his side were beaten 6-0 by Bayern Munich.
"Of course we lose a bit of self-confidence because of this," he added on Sky television. "You could see that when we had one-on-one situations, but failed to score from two yards out.
"And if you don't score goals, you can't win games. Everybody is very disappointed because the margin of defeat is too high, in truth. We beat ourselves, we wasted great chances."