Lukaku has rejoined Inter on a season-long loan from Chelsea.
Paganin said, “Lukaku comes off the back of a season in which there were great expectations around him, and it was an incredible flop for him and for the club who signed him.
“But that's now a thing of the past," he continued. “Now he's an Inter player again, and will have a great desire to demonstrate that the London interlude was only a momentary lapse.
“For (coach Simone) Inzaghi this will be the the real litmus test, he will have no excuse this time."