Petrov is now hoping to resurrect his career, which dipped at Eastlands after a stunning first season which saw City complete a league double over their rivals for the first time in 34 years.
"I don't think I have played very well for Bolton yet because of the knee injury I had at City last season," said Petrov.
"It is difficult at 31 to come back after an injury and play at your best. But I will give everything. I just want to tell Bolton fans I am not yet the real Martin Petrov - but I will be."