De Marigny, who made his first start for Italy in the 25-0 defeat to France this weekend, believes his side have what it takes to defeat the Scots and pick up only their third victory since joining the competition in 2000.
Italy's two previous wins came against Wales, and in their very first Six Nations match when they beat then defending champions Scotland 34-20 in Rome.
De Marigny is hoping for a repeat performance when the Scots return to the Stadio Flaminio on March 6.
"We fought very hard against the French with a great defence," the South African-born De Marigny said on www.gazzettadiparma.it. "25-0 is a large defeat but they are a great and strong team.
"Now the match against the Scots is the most important moment for us, we must win this game at any cost."
Like Italy, Scotland have yet to pick up a point in this year's tournament following defeats by Wales and England.
The Azzurri have welcomed full-back Gonzalo Canale back into the fold after he missed the first two RBS 6 Nations games against England and France due to a thigh injury.
Canale has been included in Kirwan's 26-man pre-selection squad to prepare for the encounter against the Scots.
New Zealander Kirwan has been further buoyed by the news that Arix Viadana full-back Andrea Masi, who missed the France defeat, has got over a left leg injury.
Kirwan has also called up Ghial Calvisano's Roberto Mandelli to train with the national team.
The Azzurri will resume training on Friday.
Squad: R Wakarua, M Castrogiovanni, A De Rossi, P Griffen, R Mandelli, N Mazzucato, S Perugini, A Lo Cicero, A Persico, C Stoica, M Barbini, M Bortolami, R De Marigny, C Festuccia, Mirco Bergamasco, G Canale, C Checchinato, Denis Dallan, Manuel Dallan, S Dellape, F Ongaro, S Orlando, S Palmer, S Parisse, S Picone, A Masi.