In early 2013 Jager relocated to South Korea at the invitation of 1984 Olympic gold medal-winning coach Kim Hyung-Tak, one of two athletes selected by the Danish Archery Federation to undergo full-time training in the country ahead of the 2016 Summer Olympics. Jager spent six months under Kim's instruction before contesting the 2013 World Championships held in Belek, Turkey. She entered the tournament's individual event with an unimpressive record, having individually failed to progress beyond the last 32 competitors in an international competition since 2011. In the event's preliminary ranking stage Jager achieved a new Danish record for a 144-arrow round, scoring 1,351 points from a maximum of 1,440. Her score was enough to qualify for the subsequent elimination rounds as the eighth seed. Jager proceeded to deliver a surprising run of results in the elimination rounds, defeating both Ki Bo-bae and Yun Ok-hee, the World Archery Federation's number one and number two-ranked archers respectively, on her way to the final. Her opponent in the gold medal match was Xu Jing, who had won an Olympic silver medal in the women's team event in 2012. After tying on five set points each over the regulation five sets, Jager outshot Xu in the subsequent tiebreaking one-arrow shoot-off, landing her single arrow closer to the centre of the target to claim the world championship title.