Hargreaves joined City on transfer deadline day after leaving Manchester United at the end of his contract in the summer.
Hargreaves struggled with injuries during his spell at United and made just four appearances in the last three seasons for the club.
“Owen is a good player, he’s been unlucky with the injuries he’s suffered in the last few years, but he’s a good player,” Vieira told reporters.
“There is no doubt about his talent and I believe he can be successful for this football club.”
Vieira continued: “He’s got the experience. He’s won the Champions League twice and he’s been successful throughout his career in Germany and England, winning league titles.
“That sort of experience can only help the club.”
