Edinburgh ran in six tries on the night, but the Italian side could not muster a single point in response, going down 48-0 for their heaviest defeat of the season so far on Friday.
Casellato's men remain rooted to the bottom of the GUINNESS PRO12 without a win to their name so far this season, but the former Azzurri scrum-half insists he remains positive.
"Nobody expected such a strong performance from Edinburgh," he told La Tribuna di Treviso. "The try after 44 seconds there has knocked the nervous system and there began the ordeal.
"Then there was the red card for Romulo Acosta; I do not condone his actions but he reacted to constant provocations and insults. Now I think he will probably be out for six weeks.
"But we have seven games still to come at home. I want to, and I will, stay positive.
"We must find some of the confidence we had shown in the games against Racing Metro, Leinster and Cardiff Blues.
"I do not want to believe that in two matches we were not able to make a counter-attack, but we were not the team we have been before and we know that now.
"It is true that we lack a strong group to trust in delicate moments, but these things are built over time.
"And we also lack a tighthead prop; we should have got one in week one but the player we had chosen went elsewhere. In my letter to Santa Claus I asked for two pillars on the right of the scrum.
"There will also be work for us to do on the psychological side to get over this but I'm the first to defend my guys. Now we just need to keep working with the best thoughts and move forward."
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