The 22-year-old handed the Midlands club a major boost when he withdrew a transfer request and agreed a new deal until 2017.
The striker netted 19 goals as Villa escaped the drop last term and Petrov believes Benteke could make all the difference in the coming campaign.
He said: "It's a big boost. The way he performed last season, the way he played, if Villa had lost him, they would probably be in bigger trouble.
"Keeping him is just great. All the fans, the players, the manager, everybody is happy that Christian is staying at the club.
"He has shown unbelievable potential. He is still a young boy and he still has a lot to learn.
"But, if he plays the way he played last season, Villa will finish very, very high this season."
Petrov sees no reason why the Belgian should receive stick from Villa fans as a result of his initial plans to quit the club.
He said: "I don't think so, I don't think they should give him stick.
"They should actually be pleased that they have a player like that in their team.
Source: PA
Source: PA