I've watched them many times including all of their european games. We should not underestimate them. They're not a fodder club. They've had some great UCL and EL matches against very strong opponents - PSG, Arsenal, Real Madrid, Liverpool, Basel, etc. They knocked out Lazio a few years ago in LE after scoring 4 goals in 2 matches and a win in Rome. They also had some major fuck ups against teams I've never heard of.
Anyway, it will not be an easy task, believe me. They're no Seria B side. They could easily be Genoa/Torino/Cagliari level if they were playing in Italy. We know that all these teams can surprise it with great performances and wins.
I am waiting for the predicted line-ups and will give more info about them. Apparently, they have some problems with the starting 11, as 2 of their best players are banned, while their starting GK is out due to a long-term injury.