The 33-year old Bulgarian midfielder has announced his retirement from the game after his battle with acute leukaemia.
Petrov, now in remission, will lead the Villa players out for their traditional lap of appreciation for the fans after Saturday's final home game against Chelsea and Lambert believes it is a great send-off for the former skipper.
"For him to lead out the team will be a great occasion," said Lambert.
"I think it will be pretty emotional for him when he does it on Saturday."
Lambert added: "Not having him around here during his illness has been huge blow, it can never be underestimated.
"Him not playing has been massive for this club. Having to try to replace someone like that - a footballer who is a fantastic player - has been hard.
"He has a heart of gold, he's nice guy. I knew him since he was 19 years of age and he first came to Glasgow and I had a good friendship with him.
"I played with him for nine years and he was always someone you knew you needed to be in the trenches with you."