The 28-year-old Spaniard finished 2011-12 with a Champions League winner's medal plus the Golden Boot after helping Spain triumph at Euro 2012.
"I was very happy with Fernando at the end of last season. He was brought in to be a fantastic striker and, hopefully, will be able to fit into our team and show his qualities," The Sun quoted Di Matteo, as saying.
"He won a lot of trophies last season, so is full of confidence. He is looking good in training. Fernando scored some important goals for us last season and people tend to forget that," he added.
Mancini claimed that Torres was a talented player and he has already shown glimpses of his qualities during training sessions at the Old Trafford.
"The price tag comes with the fact he has been superb over the years for the teams he has played for, Liverpool and Spain. So we are very confident in him," he said. (ANI )