Napoli visit San Siro knowing that victory will be enough to guarantee a place in next season's UEFA Champions League.
The clash comes just six days before the cup final with Fiorentina, in which Napoli will attempt to regain the title they won for a fourth time in 2012.
However, Benitez is focused solely on securing participation in Europe's premier club competition by getting the better of an Inter side coached by former Napoli boss Walter Mazzarri.
"It's a very important game for both teams," Benitez said. "We want to continue in Europe next season and we need to ensure third place in mathematical form - leaving no room for doubt.
"The team has to play tomorrow going all out to win. Thinking now of the final of the Coppa Italia would be a mistake; we focus on the game after the match at the San Siro."
Benitez is adamant that his team selection will not be influenced by the approaching Stadio Olimpico showpiece.
Instead, he has challenged his players to earn a place against Fiorentina with a strong performance this weekend.
"I always pick the players that I consider more prepared for every game, in this case Inter Milan," Benitez added.
"The message I have given the team has always been show me who wants to play the next game and I'll remember."
