Born in Byala, Rousse Province, Kolev underwent trials in the Litex Lovech youth academy after just two training sessions.

He progressed through all age groups at the academy, coached by specialists including Stefan Yarmov, Plamen Linkov, and Nikolay Dimitrov-Dzhaych.

The same year, he also secured a bronze medal in the Bulgarian Football Union Cup (again with the 1987 cohort at Litex).

The promising talent began training with the first team, participating in 7-8 friendly matches, but never made an official debut for the senior squad.

In the winter break of the 2011–12 season, he moved first time abroad, to play with Moldovan National Division side FC Costuleni.