Portunova broke onto the national stage at the 2013 World Junior Curling Championships where she threw fourth stones for the Russian team skipped by Alina Kovaleva. After qualifying for the tiebreaker round with a 5–4 round robin record, the Russian team won four sudden death games en route to capturing the World Junior title. It was Russia's first title at the event since 2006. They returned to defend their title the following season at the 2014 World Junior Curling Championships but lost in the 3 vs. 4 page playoff game to Sweden's Isabella Wranå. They then defeated Sweden in the bronze medal game to secure third place and bronze medals for the tournament.