The pair have scored 24 of Torino's 39 league goals this season, helping the club to seventh in Serie A.
And Petrachi believes former Fiorentina playmaker Cerci has provided a creative spark for Giampiero Ventura's side, while Immobile has blossomed since arriving on a co-ownership deal from Juventus.
"I was hoping Cerci would perform for us this season, and he has delivered. It’s clear that when he's 100 per cent, he brings so much to this team," Petrachi told Tuttosport.
"He is the sort of player that can produce a moment of magic - he makes the difference.
"Immobile? I have to say he is visibly growing in front of our eyes. This summer Ventura and I were the only ones that could see his potential.
"No one was willing to bet a euro on him, but Ventura and I did, and so far we've won."
Torino make the short trip to Serie A leaders Juve for the Turin derby on Sunday.
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