Baby faces Ireland as Valbon ruled out
Benoit Baby, 21, has been promoted from the replacements' bench and will win his first cap on Saturday. David Marty comes on to the bench.
Replacement hooker William Servat was also injured during a tough training session with the A team and will have a scan today.
Elsewhere, Italy assistant manager Carlo Checchinato insists the Azzurri have selected their most in-form players for the RBS 6 Nations clash with England on Saturday.
Coach John Kirwan has made a number of changes to his starting line-up for the Twickenham encounter: Gert Peens has been brought in as a goal-kicking full-back, Salvatore Perugini comes in for Leandro Castrogiovanni in the front row, winger Kaine Robertson deputises for Mirco Bergamasco, who has been shifted to centre, while lock Carlo Antonio Del Fava makes his first start for Italy.
Checchinato said: "This appears to be a good team.
"It is solid but fast, with (Ludovico) Nitoglia and Robertson able to run well on the wings.
"Also, Salvatore Perugini has gained a first start after playing well as a substitute and impressing in the November Test matches.
"We are confident in Gert Peens' kicks delivering the points we are missing at present, and we are giving a chance for lock Carlos Antonio Del Fava to form a partnership with captain Marco Bortolami and make a strong pairing in our side."
With both sides without a win in any of their three games so far, the match could decide where the wooden spoon ends up.
Italy will start as rank outsiders but Checchinato feels the Azzurri have nothing to lose.
"A defeat against the English would be normal for us but if anything comes our way, I'm sure we will be ready to take our chances," he said.
Italy's opponents have a new captain in Martin Corry, who has been backed by his World Cup-winning skipper, Martin Johnson "Jonno's not one to go over the top about anything," said Corry.
"He sent me a text message saying something like: 'All the pressure's on you now, the country expects'."
England have lost all three of their championship games and are level with the Azzurri at the bottom of the table without a single point.
"Every time we take the field the public should expect England to win. We have let ourselves down so far," admitted Corry.
"The situation we find ourselves in is one we don't want to be in and never want to be in again in the future.
"We have a massive game on Saturday which maybe won't put everything right, but it will hopefully go some way to doing so. "The next step is the biggest of all winning matches and then winning consistently to do justice to what has happened in the last three games."
