The Poland striker, who will leave for Bayern Munich at the end of the season, has recovered well from the strain which saw him miss the 1-0 victory over Freiburg last Sunday and returned to training on Thursday.
Lewandowski's 15 Bundesliga goals in 2013-14 mean his return will strengthen Dortmund's attacking options for Saturday's visit of Borussia Monchengladbach, although fellow BVB star Marco Reus is unlikely to feature due to a thigh problem.
"Robert Lewandowski has recovered from his injury," Klopp told reporters. "He could be available against Gladbach.
"If nothing extraordinary happens overnight, then Marcos Reus will not be able to be there. Jonas Hofmann could start, he's a very important member of the squad."
Dortmund lost 2-0 against Gladbach earlier in the season and, though Klopp thinks that result was warped considering the performance his team put in, the BVB trainer thinks the visitors have improved since.
"We were incredibly unlucky when we last met them," he added. "Gladbach have been much-improved under Lucien Favre.
"Gladbach are a quality side. Juan Arango, Max Kruse and Raffael are exceptional players."