United boss Sir Alex Ferguson is committed to playing most of his fringe players in the Group F dead rubber, with many of his senior stars remaining in Manchester.
Along with Wes Brown and Michael Carrick, Rooney was the only member of the Red Devils' starting line-up from Saturday's victory over Derby to make the flight to Italy, with Ferguson confirming the 22-year-old will wear the captain's armband.
"He has been pestering me for quite a while now, so I have given in," said Ferguson.
Rooney has done the job once before - in last season's European victory over FC Copenhagen at Old Trafford - and the fact he has got the job ahead of John O'Shea, who skippered United in their Carling Cup defeat to Coventry earlier this season, indicates Ferguson does see Rooney as future captaincy material.
The England international will need to be at his very best if he is to guide United to victory given the lack of experience within the travelling squad.
Danny Simpson, Jonny Evans, Nani, Darren Fletcher and Louis Saha do have first team experience. However there are five completely unexposed youngsters in the 20-man party, including reserve team top scorer Febian Brandy and last season's youth team captain Sam Hewson.