A place in the Europa League last 16 is up for grabs and Carvajal has said that a "very, very good team" stands in the German side's way.
"It will be important to get a result in the home game to give us a cushion when we go to Benfica," Bundesliga.com quotes Carvajal as saying.
"They're a very, very good team and they will make life really difficult for us. It will definitely be a tough challenge for us to beat them."
Leverkusen are currently third in the Bundesliga, a point behind Borussia Dortmund.