 Kọ itẹsiwaju fun paragirafi yii - Ni Oṣu Karun ọdun 2015 ni Awọn ere Yuroopu akọkọ ti 2015 ni Baku, Kozlov gba ami ẹyẹ goolu pẹlu Ẹgbẹ Russia ni awọn ọkunrin 4 × 100 m medley pẹlu Daniil Pakhomov, Anton Chupkov ati Filipp Shopin ti o fi ọwọ kan ni 3:36.38, igbasilẹ agbaye tuntun ti ọdọ ti o fọ igbasilẹ ti tẹlẹ ti Russia ni 3:38.02 ni Awọn ere Olimpiiki Ọdọ 2014 : . ati ni 4 × 100 m ti a dapọ freestyle pẹlu Arina Openysheva, Elisei Stepanov ati Mariia Kameneva ni akoko ti 3:30.30. Kozlov tun gba idẹ idẹ ninu awọn ọkunrin 100 m freestyle kọọkan ati pẹlu Ẹgbẹ Russia ni awọn ọkunrin 4 × 100 m freestyle. 