Season 2004-05 is arguably the most important in the club's history, as the team managed to promote to the A PFG, or first tier of Bulgarian football, for the first time.

It has carried the names Ustrem, Gotse Delchev, Yane Sandanski and Cherveno zname throughout its history.

It always stood in the shadows of the other more successful clubs from the region, such as Pirin Blagoevgrad, and Belasitsa Petrich, who regularly competed in the A Group.

Before their first year of playing in A PFG, Vihren's owner decided to bring players from other countries to bolster the team's chances of surviving in the top flight.

In season 2007–08, Vihren's owner, Konstantin Dinev decided to bring Portuguese coach Rui Dias.

In January 2008, Vihren signed notable Greek players Christos Maladenis and Dimitrios Zografakis.

The following two seasons were spent in the second tier, but financial problems overwhelmed the club, forcing its folding in 2011 and withdrawal from the B Group.

Brazil Cape Verde Croatia France Spain Greece Hungary Macedonia Nigeria Portugal Serbia Uruguay Argentina Venezuela