The pair trained on Sunday, but midfielder Thiago was absent as he recovers from a knee injury.
Liverpool has won both of their Champions League games this season and is top of Group D.
This will be Liverpool’s first European match against the Italian side and Klopp is expecting a tough game.
“They obviously have a really good atmosphere, a good mood and are a proper fighting unit,” said the German.
“They are very well organised; play their system with 100% conviction, they know exactly what everybody has to do.
“I know how good they are. I actually enjoyed the analysis, I enjoyed watching them because it’s really interesting.”
Premier League leaders Liverpool will be playing their sixth game in 18 days.
Matip has only featured twice this season and missed the past four matches, while Keita has been absent for five games because of a muscle injury.
“We have, in the moment, more centre-halves available than we probably will line up together, which is good,” added Klopp.