Despite a second-half goal from Andre Schurrle, Borussia Dortmund have work to do to reach the last eight of the Europa League.
Peter Stoger conceded Borussia Dortmund were well off the pace during Thursday's 2-1 Europa League defeat to Red Bull Salzburg on home soil.
The Austrian side stunned their hosts at the start of the second half, Valon Berisha scoring twice in the space of seven minutes.
While Dortmund halved the deficit with a close-range finish from Andre Schurrle just after the hour, they will now have to score at least twice in the second leg to progress to the quarter-finals.