Fa'amausili, a former Australia Schools and Under-19 international, injured himself in a recent training session but the powerful prop has been passed fit for the start of European competition.
In a considerable boost, Connacht's talismanic captain John Muldoon features in the selected squad and is set to lead the side for their pool opener.
Muldoon fractured his arm when playing for Ireland against New Zealand during the summer tour, and although a groin complaint prolonged his absence from the westerners' starting line-up, he is now ready to return.
Prop Brett Wilkinson is poised to win his 100th cap for Connacht this weekend, in the province's first ever encounter with the little-known Italians.
"We are expected to win so it is a potential banana skin. But it's a match we're very much looking forward to. We've parked the Cardiff game and the Magners League, and it's a nice break to be going into Europe," said Connacht coach Eric Elwood.
"There are bigger games ahead, and we have to show faith in our squad, give other players an opportunity and I am sure some of them will be given their chance to step up to the plate this weekend.
"The new Connacht want to do well in every game we play, and that's why I was really disappointed in Cardiff, because I thought we had good opportunity. We created 10 line breaks but just had too many turnovers."
Commenting on a pool which also includes Bayonne and Harlequins, Elwood added: "If we beat Cavalieri, it will give us confidence going into next week's home match against Bayonne which will be a very tough encounter.
"Bayonne got off to a flyer and are still in the top half of the French Championship, while Harlequins are always difficult.
"If you look back even last season you had Wasps, Gloucester, and some big French teams. It's a competitive tournament. It may not be top tier, but if you look at the teams that have won the Amlin Challenge Cup, they are all big clubs."
CONNACHT Squad (v I Cavalieri Estra) - Backs (10): Cillian Willis, Frank Murphy, Ian Keatley, Miah Nikora, Fionn Carr, Aidan Wynne, Shane Monahan, Darragh Fanning, Troy Nathan, Niva Ta'auso.
Forwards (13): Brett Wilkinson, Rob Sweeney, Ronan Loughney, Barry Fa'amausili, Dermot Murphy, Adrian Flavin, Michael Swift, Bernie Upton, Andrew Browne, Mike McComish, Michael McCarthy, Johnny O'Connor, John Muldoon (capt).