In July 2014, Lake and her coaches initially planned to have her compete in the 2014 Commonwealth Games in Glasgow, but decided against it and headed for the 2014 World Junior Championships in Eugene, Oregon instead. She began her campaign at the championships on 22 July with the 100 m hurdles, finishing fourth in the third heat and 12th overall with a time of 14.29 s. She stormed to the top of the heptathlon table with 2,096 points, setting a British junior record of 1.94 m in the heptathlon high jump. The only athlete to have cleared 1.85 m, she attempted a world youth record and British senior record height of 1.97 m, but failed to clear it. She began the afternoon session with a win in the heptathlon shot put, throwing 14.17 m to take her total to 2,901 points. She closed the day with the 200 m, finishing in third place both in the third heat and overall behind German world youth champion Celina Leffler and Dutch athlete Nadine Visser to end with a total of 3,821 points and remain at the top of the heptathlon table.