The former Inter centre-forward is returning on-loan from Chelsea.
Semplici told La Gazzetta dello Sport: "Lukaku will be devastating. He's going to increase Inter's value.
"He has great desire and determination and when he was there he felt all right. He wants to come back after an unhappy experience at Chelsea."
He added, "Pogba, on the other hand, returns to Juve with great conditions: and with a mentality."