Firmino is in line for a recall after missing Friday's Premier League win over Chelsea at Stamford Bridge due to injury.
"Roberto is in training," said Klopp.
"The medical department told me he could have played against Chelsea, but I have heard the word risk too often so I decided no. I was very happy that it worked out.
"They told me if I gave him three days he would be perfect. Today is the fourth day."