A win at the Stadio Sant'Elia would lift Montella's fourth-placed team level on points with Napoli in the Serie A.
Fiorentina enter the clash as deserved favourites against a Cagliari side sitting 14th and winless in their past six matches, including three straight losses.
But, perhaps trying to ease the pressure on his team, Montella said the hosts could be 'devastating' on the counter-attack.
Fiorentina are unbeaten in their past nine matches in all competitions, but were held to a 3-3 draw by Genoa last time out.
"Cagliari are a mature team. They're a side that I like a lot," Montella told reporters.
"They can be devastating on the counter-attack and have some real quality in their side that are capable of quality.
"We can't feel sorry for ourselves after recent results. This is football. Sooner or later things will go our way."
Montella is content with his team's transfer activity in January as they added Sunderland defender Modibo Diakite to their squad on loan for the rest of the season on deadline day.
"Diakite? We needed a man for that role. Modibo has great physicality. We are absolutely delighted to have brought him in," he said.
"I'm satisfied with what we've done in the market, but let's see what happens."
