Tom Williams is called up at full back, with Dan Fish moving to the wing, while the other change sees Chris Dicomidis named in the second row.
Wales international lock Lou Reed could make his comeback after four months ruled out as he is named among the replacements.
French prop Benoit Bourrust, back row Ellis Jenkins and centre Dafydd Hewitt are also named among the replacements.
Director of Rugby Phil Davies said: "It's a huge game for us and there is absolutely no hiding away from that fact. It is the last of a four-game stretch when we wanted to climb the table and so only a victory is good enough.
"The effort from the players over the last few weeks has been great, but there are periods in matches where we drop off our standards.
"We have played teams in the top four in recent weeks and you have to play for 80 minutes. We ran Leinster close for 40 minutes but a few lapses and they were gone. That cost us and we have got to stop that happening.
"This weekend we have got to play for 80 minutes in Italy. If we do that we are starting to create and score more tries so can get the result we all want."
Cardiff Blues: 15 Tom Williams, 14 Harry Robinson, 13 Isaia Tuifua, 12 Gavin Evans, 11 Dan Fish, 10 Gareth Davies, 9 Lewis Jones; 1 Sam Hobbs (c), 2 Kristian Dacey, 3 Scott Andrews, 4 Chris Dicomidis, 5 Filo Paulo, 6 Rory Watts-Jones, 7 Josh Navidi, 8 Robin Copeland
Replacements: 16 Rhys Williams, 17 Thomas Davies, 18 Benoit Bourrust, 19 Lou Reed, 20 Ellis Jenkins, 21 Tomos Williams, 22 Simon Humberstone, 23 Dafydd Hewitt