In summer of 2001 Kolev joined CSKA Sofia and was loaned to Beroe Stara Zagora on a three-month deal. He made his debut for Beroe on 10 November 2001, keeping a clean sheet in a 0–0 draw against Levski Sofia. In early 2002 he returned to CSKA. On 11 May 2002, Kolev made his first appearance for CSKA in a 0–2 loss against Slavia Sofia. He started 2002–03 season as the first choice goalkeeper in CSKA and kept a total of 13 clean sheets in 24 appearances and conceding only 14 goals at less than a goal a game as CSKA won their 29th A PFG title.