Salzburg defender Andreas Ulmer accidentally wore a Leipzig shirt during the second half of Tuesday's Champions League qualification match against FK Liepaja.
Soft drink giants Red Bull own both Austrian side Salzburg and new German Bundesliga top-flight club Leipzig.
Neither team are allowed to display any brands in their club badge in European games as well as matches in the German professional tiers because of restrictions by UEFA and the German Football League .
This led to confusion in Salzburg, where the Austrian champions began their campaign with a 1-0 win against the Latvian champions.
- KURIER SPORT (@KURIER_SPORT) July 14, 2016
After changing jerseys at half-time, RB Salzburg defender Ulmer was pictured wearing an outfit from the twinned-club RB Leipzig, who have an identical outfit except for the club badge.
Ulmer's badge now prominently displayed the "Leipzig" lettering where it should have read "Salzburg."
According to Austrian paper Kurier, the club only realised their mistake during the postmatch interviews in the mixed zone, but by that time pictures of Ulmer with the wrong badge had already been mailed out to papers by their photographers at the ground.
Kurier suggested that a shipment from the club's outfitter Nike might have gone wrong.
UEFA have yet to react to the incident.