La Viola need all three points from Sunday's Serie A trip to Pescara and a Milan defeat at Siena to guarantee Europe's premier club competition comes to Tuscany next season. If Milan draw, Fiorentina would need a rout to secure third place.
Montella knows his side's destiny could be determined by events at the home of fierce rivals Siena, who were relegated last week, while Pescara dropped out of the league weeks ago having struggled to accrue 22 points.
The former Roma striker told La Repubblica: "We will try to win because we do not want to have any regrets during our holidays.
"Pescara is an important game and it is our duty to do our best. Nobody is allowed to think about what might happen in Siena, we can only play our our own game.
"The club that deserves the Champions League will get there."
Montella did, of course, offer words of encouragement to Siena boss Giuseppe Iachini, whose side will be playing for pride at the Stadio Artemio Franchi but could inadvertently boost their rivals.
"The Bianconeri are a good side and Iachini is a proud person," he added. "I respect him a lot and I'm sure Siena will give them a game."
Defender Michele Camporese, midfielder Mohamed Sissoko and striker Marcelo Larrondo are sidelined through injury for the trip to Abruzzo.
Pescara's young coach Cristian Bucchi must cope without a host of injured first-team regulars including Per Kroldrup, Ante Vukusic, Gaetano D'Agostino, Vladimir Weiss and Ivan Pelizzoli.
Defender Antonio Balzano is suspended as the Delfini prepare to limp back into Serie B after failing to make an impact in the top flight.
Bucchi would not be drawn on his own future as rumours grow surrounding the return of Czech tactician Zdenek Zeman, who sealed the club's promotion from the second tier this time last year.
"I'll talk to the club next week and we'll decide what my future holds together," Bucchi told Gazzetta.it. "I still want to play a part, even if that means taking control of the youth team again.
"Fiorentina have played the best football of anybody this season, them and Juventus. Who is my favourite player on their team? Borja Valero - he's exceptional."