The 36-year-old has been out of action ever since he injured his ACL in United's Europa League quarter-final clash against Anderlecht in April.
However, he made his first appearance in a United shirt this campaign during United's emphatic 4-1 win over Newcastle on Saturday.
That game also saw the return of Paul Pogba and Marcos Rojo, something Zlatan believes will help his team catch Manchester City at the top of the Premier League table.
"I think we can chase City, why is it not a possibility?" said Ibrahimovic. "We are all here because we want to win and we need to because they are first.
"I can talk of what Paul brings - big quality. Today it was like he hasn't been injured for a month, he brings such big quality, a different quality and I bring experience and mine.
"I try to help the guys much as possible and do what I can.
"This week the manager has been very happy because he has a full team for the first time this season and as a coach you want those opportunities and alternatives to make changes.
"I think there is a possibility of winning everything. We were early into it last year and won two trophies and we are stronger this season. We believe we can do it."