Levski Sofia players and staff were threatened during a road blockade set up by disgruntled fans of the Bulgarian team.
Angry supporters attempted to storm the team coach following their 1-1 draw at Pirin Gotse Delchev on Wednesday evening to demand an explanation for the below-par display.
Police arrested 20 Levski fans for public order violations during the incident and the team's players had to be rescued from the mob, Reuters reports.
Levski currently lie in second place in their domestic league, one point behind Ludogorets.