He started his senior pro career with
OFK Beograd in 1981 at only 16 years and 16 days of age (at that time the youngest ever in the Yugoslav First League), before moving on to
Red Star Belgrade in 1983 where he stayed until 1990. After appearing in one league game for Red Star in 1990/91 season, he transferred to Dutch club
FC Twente and stayed there for two seasons. He played several matches for
Beşiktaş in the 1992-1993 season and scored 4 goals, before returning to the
Netherlands with
SC Cambuur. Mrkela holds distinction as the youngest player ever to play for
SFR Yugoslavia national squad. He was only 17 years and 130 days old when he made his national team debut on 17 November 1982 during a
Euro 1984 qualifier versus
Bulgaria in
Sofia. Head coach
Todor Veselinović brought him on in the 17th minute in place of injured
Zvonko Živković. However, despite a lot of early promise, Mrkela would go on to make only 5 national team appearances, scoring 1 goal. ==Post-playing career==