The Argentinian international seemed certain to leave the club this summer, but a deal didn't happen and the striker still remains part of the manager's plans.
He made his first start of the season against Wigan on Saturday and, although he missed a penalty, Mancini was pleased with his all-round contribution.
The manager admitted: "Carlo is not 100% at the moment but I am happy for him because for me he played very well with Sergio.
"He missed a penalty but this can happen - usually he scores. It was important for him to start, to play and to play well, and maybe in two or three games he will be 100%."