Merkulova's junior international debut came in 2008. After winning all-around gold at the 2008 Junior Grand Prix Final in Bratislava and in the 2010 Junior Grand Prix in Innsbruck, she won the all-around gold at the 2009 Pesaro Junior World Cup, the 2010 Saint Petersburg Junior World Cup and won 3 gold medals in team, rope and ball at the 2010 European Junior Championships. Merkulova then won gold at the inaugural Youth Olympic Games held in Singapore.