The match at the Generali Arena is Chelsea's first away fixture in Europe since Roberto Di Matteo was sacked following the holders' exit from the Champions League group stages.
"This is a massive city, massive club and a massive competition," Benitez said. "We are really pleased to be here. Obviously, you cannot change things. The Champions League is a massive competition, but the Europa League is also a massive competition."
"We play against an historic team. We're really pleased and, for me, I try to give my players the right message. We know it will be tough. It's against a great team, a great club and a great city."
Benitez has a contract until the end of the season and would not look towards the possibility of taking permanent control should Chelsea win the Europa League.
"We have to concentrate on the future and the future is tomorrow," said Benitez, whose position could yet be under threat with four wins in 11 games.
"I cannot talk about what will happen in three months' time. We have to concentrate on this competition - it's quite difficult - and tomorrow will be a tough game, so that is my priority."
The Blues are at near full strength, with David Luiz suspended, Demba Ba ineligible and Victor Moses and John Obi Mikel rested following their African Nations Cup win with Nigeria.
Captain John Terry was the main fitness concern for Chelsea after missing the 4-1 Barclays Premier League win over Wigan with an inflammation on his knee. He is fit to be selected.
Benitez said: "There was no reaction to his knee (from training), that is positive. It's a question of time."