The Reds travel to the Belgian province of Limburg for the third match of their Group E Champions League campaign.
Felice Mazzu's side bounced back from a 6-2 defeat at Salzburg on matchday one to then hold Napoli to a goalless draw in their next European fixture.
Previewing the encounter onboard the team flight, Klopp told Liverpoolfc.com: "They will be tough.
"Yes, they lost against Salzburg but it was completely even for the first half an hour. Salzburg scored four goals in a short period and that was obviously impressive. But against Napoli, Genk showed their other face.