The Bundesliga outfit were brushed aside by the European champions after making a bright opening and Arnautovic, who was an Inter player last season, recognised the gulf in quality between the two teams.

"We played against the best team in the world today," said the Austria striker.

Bremen captain Per Mertesacker also felt the title holders and Serie A champions were in a different league.

"You could see a clear difference between the two sides," he said on his club's website.

"However, we shouldn't forget who we were up against and all the replacements we had to make to our side."

Indeed, Bremen made the trip to Milan without the likes of Torsten Frings, Claudio Pizarro, Naldo and Clemens Fritz, who were all injured.

"We could have done with our more experienced players today," said the club's director of sport Klaus Allofs.

"At this level, it is hard to compensate for the losses of such players."

Bremen will now turn their attention back to the Bundesliga and a tricky trip to Bayer Leverkusen on Sunday.