It's really hard to point out Zaragoza's strengths without mentioning Apoño and Helder Postiga. When Málaga decided to sell the Spanish midfielder during the past winter break, Zaragoza ended up getting a really good player that can keep the ball and also set up his teammates.
Portuguese striker Postiga is what the team needs upfront to compete with some teams that maybe have a better overall roster. He was Portugal's starting striker during the past UEFA Eurocup, and he has already notched four goals in this Liga BBVA season. He's quite a dangerous threat in the aerial game, so Real Madrid will need to stay focused once again every time Zaragoza gets a corner-kick or a foul. Other than that, Postiga isn't that great, so Varane and Pepe will only be warming up before facing Dortmund's Robert Lewandowski next Tuesday.
Zaragoza's goalkeeper is great. Roberto was one of the Liga highlights last season, and he is arguably one of the best goalkeepers outside Real Madrid and Barcelona. Furthermore, some tabloids reported that Real Madrid was interested in bringing him to compete against Iker Casillas. It would've been a great signing for the team, but it was only the media speculating about Roberto's agent, Jorge Mendes.
That way, Zaragoza has a good line in Roberto, Apoño and Postiga. But they lack a competitive defender. Jiménez has been playing with Sapunaru, González, Paredes and Abraham, and that's clearly not enough to contain Real Madrid at the Santiago Bernabéu. Zaragoza also lost Lafita to Getafe this summer, so it will be a challenge for them to repeat last year's miracle.
One way or another, Zaragoza has won two games in a row, one of them against Sevilla, so Real Madrid should still be careful about this venue. Thanks to those two wins, Zaragoza is currently ninth in La Liga's table, but it's still too early in the season to judge whether they will be able to avoid relegation for the second year in a row. It all seems that they will fight against Valladolid, Rayo, Osasuna and Granada.