Lukaku opened the scoring four minutes into the second half at San Siro with his 10th goal in his last nine European appearances, but Gladbach had the victory in their grasp after Jonas Hofmann struck late on.
Antonio Conte’s side tasted defeat to city rivals Milan in Serie A last time out and looked set to be heading for another loss when Hofmann raced through to slot home following Ramy Bensebaini’s equaliser from the spot.
Yet Inter had the final say, with Lukaku on hand to bundle home his second from a corner and snatch a share of the spoils.
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