Austria striker Arnautovic rammed home Inter's winner with 11 minutes left at the San Siro after Jan Oblak failed to hold Lautaro Martinez's shot. The 34-year-old turned jeers into deafening cheers with his goal, which came after a series of missed opportunities left home fans wondering whether Inter would get the win their performance deserved.
His worst miss came just after the hour mark as he ballooned over a sitter, a dreadful finish which came before and after failed attempts to latch on to promising balls. Arnautovic has had a hard time since returning to Inter on loan from Bologna last summer and those misses further frustrated supporters.
However, thanks to him Simone Inzaghi's side now take a slender lead to Madrid, where they will face Atletico in the decisive second leg on March 13.