We may be favourites to progress from our Europa League quarter-final with Slavia Prague, but the Czech's side record speaks of their threat.
Two seasons ago, they won a point against both Barcelona and Inter in the Champions League, and in the Europa League they can boast victories against the likes of Sevilla and, this season, Leicester and Rangers.
Mikel Arteta certainly is not taking them lightly.
"They are a really strong side," he said. "I think in the last few years, competing at the highest level, they've always been in the game and made it really difficult.