The Germany attacker has missed Dortmund's last two games after tearing a thigh muscle in the 5-1 hammering of Werder Bremen earlier this month.
Klopp revealed at a press conference on Thursday that Reus is set to feature in Mirko Slomka's first game in charge of Hamburg.
"Marco Reus was able to give 100 per cent in training and looked good. He should be fit to play," said the Dortmund coach.
Klopp's side travel to Imtech Arena in fine form, having won their last four matches to put the heat on Bayer Leverkusen for second spot in the league as well as reaching the semi-finals of the DFB-Pokal.
He said: "We can't go to Hamburg with our new-found confidence expecting to face a weak opponent.
"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 management 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 be special and 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."
