Celtic undone by Milan
In Glasgow, Celtic struggled against Serie A leaders Milan who were 2-0 up at half-time thanks to goals from Rade Krunic and Brahim Diaz.
Mohamed Elyounoussi reduced the arrears after the break, but Jens Petter Hauge broke clear to secure Milan's Group H win in stoppage time.
Milan were so comfortable that they could afford to take Ibrahimovic off just after the hour.
Celtic have now lost two games in a row at home after losing to Glasgow rivals Rangers at the weekend. Milan have kept up their fine start to the season.
Milan are at home to Sparta Prague next Thursday while Celtic visit the French city of Lille.