The two sides will meet in the first leg at the Allianz Stadium barely three weeks after Juventus inflicted a 1-0 defeat on Inter at the San Siro in Serie A.
That defeat is part of a three-game losing run for Inter, which has seen them drop to fourth on the table.
Juventus on the other hand have won their last three matches and have climbed to seventh despite being handed a 15-point deduction for financial misappropriation.
Simone Inzaghi's side might be going through a tought period but Allegri is adamant it is just a blip.
"It's a different competition, but it's always Juventus [versus] Inter," he said. "We must create the conditions in order to qualify.
"It's not an easy game. Inter remain a strong side, regardless of the moment [they are in]. Actually, it is in these moments that we have to keep our attention.
"Too much praise for Juventus could lead us to lose touch with reality. We face a strong team, physically and technically. They have lost a few games, [but] we need to pay attention."
"I think Inzaghi is doing a great job," he added. "Inter are a strong team regardless of their moment. It's dangerous to meet these teams now. We need to be fully focused."
