Born in Carmagnola, Piedmont, from Sicilian parents, Lentini grew up playing in the Torino youth system. After occasional appearances for the senior side, he spent the 1988–89 season on loan with Serie B club Ancona. He returned to a Torino team that had been relegated, but scored 6 goals as they won the Serie B title and were promoted straight back to Serie A for the 1990–91 season. Under the coach Emiliano Mondonico, he immediately won the Mitropa Cup in 1991, and he reached the final of the UEFA Cup in 1992, also achieving a third-place finish in Serie A during 1991–92 season.