The Champions League Group F clash at the San Siro has an extra edge after the European champions signed Ibrahimovic and defender Maxwell from Inter and striker Samuel Eto'o went the other way.
Ibrahimovic told a news conference on Monday he was relishing the challenge of returning to his former club even if he was not quite back to full fitness after a hand injury and was still getting to know his new colleagues.
"I'll do everything to score (on Wednesday) because I play for Barca now," the Sweden striker said.
"I don't know what to expect from the fans but I will go there and do my best and hope we win," he added. "People know my quality and I know my quality and for me it's an obligation to win every match I play."
Ibrahimovic was a match winner for Barca in La Liga on Saturday, scoring one goal and setting up Lionel Messi for another in a 2-0 win at Getafe.
He said he was feeling much better physically after the hand injury disrupted his pre-season training and he was glad to have played the full 90 minutes.
"Where I am (physically) I don't know but I am improving and working hard," he said.
"I also need to get to know my new team mates better to best use my chances.
"It's normal to have to adapt and it's something that only comes in time. It's important for me to play games and get my rhythm. The more games I play then the more you will see the real Zlatan."
Ibrahimovic said Inter had a much stronger squad this year.
"I would say they are among the favourites to win even the Champions League. I am sure that the Champions will come for Inter one day."
