The Germany international has missed BVB's last two games after tearing a thigh muscle in the 5-1 hammering of Werder Bremen earlier this month, but is now poised to make his comeback.
"Marco Reus was able to give 100 per cent in training and looked good," Klopp told reporters. "He should be fit to play."
Dortmund travel to the Imtech Arena having won four matches in a row - a stark comparison to the seven successive defeats Bert van Marwijk's men had before his sacking last weekend - but the Schwarzgelben boss expects Hamburg to be rejuvenated under new coach Mirko Slomka.
"We can't go to Hamburg with our new-found confidence expecting to face a weak opponent," Klopp continued.
"We'll have to see how they set themselves up, but ultimately we've got perform to our capabilities.
"We need to work hard. We can't underestimate Hamburg. They've got a fresh start under Mirko Slomka It's not the first time a team has changed coaches right before facing us.
"Slomka has spent time with his squad and if they buy into him then it'll be like a fresh start. The relegation battle has started for some sides. So I'm expecting a fight in Hamburg.
"Hamburg will have a special atmosphere, they will celebrate every tackle. Hamburg don't need any sympathy from us, but they won't get any from us either."
Mats Hummels and Ilkay Gundogan remain among the Signal Iduna Park stars sidelined for the Hamburg clash.
