A hamstring tear means Sale Sharks scrum-half Peel will be out of action for at least a month.
Phillips is promoted from the replacements bench to the starting line-up and resumes his regional partnership with Ospreys fly-half James Hook, whilst London Irish scrum-half Warren Fury is handed the chance to win his third Wales cap as a replacement.
Scarlets scrum-half Martin Roberts has been ruled out of the trip to face the Azzuri with a rib cartilage problem, but his fitness will be judged again next week with a view to being in contention to face Ireland at the Millennium Stadium the following weekend.
“Martin has not been able to take a full part in training this week, but will be re-assessed early next week,” said Wales physio Mark Davies.
“Dwayne will be out for a minimum of four weeks after a scan revealed a tear to his hamstring and we all wish him a speedy recovery.”