No Sergei did not play as an OA in the OHL. Oddly enough though he was eligible to play in the AHL as a 19 year old, but the Habs decided he should go back to the OHL to develop several aspects of his game including leadership roles. He wasn't happy about it, but it was better for him
He was drafted by the Habs and then shortly after that he was drafted in the CHL import draft by the Knights in '05. He played 2 years in London. Started in hamilton the next year and the rest is history as they say.