I do not know the situation of all players of Zaragoza about this match and if any of these is suspended or injured for play this week, but anyway, Zaragoza has their best players in attack and mildfield, no doubt about this.
The young ZAPATER, is the surprise of this team this season. A "worker" of the mildfield but with a huge quality, recovering and sending balls to their forwarders always in good conditions. More players, the defender ALVARO (he has scored the goal of Zaragoza against Fenerbaceh in their first match) is strong defender but with several tactital problems, and in attack, Zaragoza has very good players, above of all, SAVIO a fast player very very dangerous always and VILLA (their best player IMO), the top scorer of this team and probably, with a good future. Also, the Argentinian Galletti is a player with a good level.
But in the other side, Zaragoza has problems in their defence and Goalkeeper. They are scoring goals easily but they are conceding goals in the same way too. IMO, If is not possible score a goal for Zaragoza in Vienna, FAK has important chances to qualify for the next round. Zaragoza is showing nervous every match in their own stadium and their public is very strange because they are supporting to their team just if they are with advantage in the scoreboard.
Also and as commented in my previous post, Zaragoza has experience in these kind of matches because they are reaching every season in Spain, at least, the semi-finals of domestic Cup (except this year, where my team ATHLETIC is in the semi-finals with Betis, Osasuna and Atletico Madrid).
And believe me, players and coach of Zaragoza are taking seriously FAK but their supporters thinks that you are a weak team.................It was the same in your match against Athletic and finally you are in next round. FAK can do it again!