The 38-year-old, who signed until the end of the season with the option of an extra year, started for Milan in a friendly against local team Rhodense on Friday.
Milan won the game 9-0 at their training ground, with Ibrahimovic scoring and providing as assist for Hakan Calhanoglu.
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The forward, who could make his Serie A debut against Sampdoria on Monday, was unveiled earlier in the day.
"At 38, I had more requests than at 28," said Ibrahimovic, who was a free agent after leaving LA Galaxy in November.
"I was looking for the adrenaline inside of me, to ensure I get the best out of myself."
Ibrahimovic saw his last stint in Europe hampered by a knee injury during his time at Manchester United.
This time around, the mercurial forward has said vowed to “shoot from 40 metres” instead of shoot.
"Many told me it would be impossible to come back [from the injury]," he said. "I worked hard and to the point I can still play now.
"[It's] impossible to play like I did 10 years ago, but I know what I need to do: instead of running, I shoot from 40 metres!
"I'm meaner than before. They know what I am like, how I train and play each match.
"You have to work hard. You have to know how to suffer, otherwise you don't reach your maximum potential. Not everyone likes to suffer but I do... and I expect a lot from my team-mates."
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