Playing career Kotsev started his playing career with Bulgarian side
FK 13. After that, he signed for
Lausanne-Sport in Switzerland, becoming the first Bulgarian to play abroad and helping them win the league title.
Managerial career In 1960, Kotsev was appointed manager of Bulgarian club
Cherno More. After that, he was appointed manager of
Sudan. In 1972, he was appointed manager of
Beroe in Bulgaria. In November 1974 he spent 1 and a half month in
Greece as the manager of
Egaleo. ==Honours==