Career
He has played in Romanian Liga I club Oţelul Galaţi where his contract with the Romanian Liga I club Oţelul Galaţi was terminated after just a few appearances for the club He than had a brief spell in Kazakhstan, before returning to his former club Football Club Levadia Tallinn. After leaving Levadia Tallinn, Ratnikov played for Esiliiga club Saskatchewan Kiviõli Tamme Auto, before returning to the Meistriliiga halfway through the 2012 Season after signing with his father"s side JK Tallinna Kalev.
Prior to his move to Romania, Ratnikov had spells at Estonian Meistriliiga clubs Maag Tammeka Tartu, Levadia Tallinn and Bulgarian team Beroe Stara Zagora.