Manolo Jimenez's men are without a win in 2013 and are desperately close to dropping into the bottom three.
Los Blancos visit having captured second place from their city rivals Atletico Madrid in the league table.
They're further boosted by their recent progression in the Copa del Rey and the Champions League too.
The international break, despised by many clubs, could have had a positive effect in allowing Zaragoza to get some of their key players back to fitness.
Goalkeeper Roberto has been back in full training and will hope to take the No. 1 spot back of Leo Franco.
Apono, who went off injured against Valencia after a goal and an assist, is also hoping to be given the all clear to return against Los Blancos.
Longer-term absentees Franco Zuculini and Ivan Obradovic remain sidelined though.
Real Madrid will be checking on the fitness of their returning internationals this week.
Xabi Alonso has struggled for fitness recently, but played 90 minutes for Spain on Tuesday night and may once again be rested for his club side this weekend.
Angel Di Maria appeared for Argentina on Tuesday night in Bolivia. He had previously been out since Madrid's win over Manchester United, so his fitness will be assessed on his return to Spain.
Iker Casillas—despite being in the advanced stages of his recovery—remains out.
Last season Jimenez achieved what many people had already written off.
Rock bottom with 12 games left and nine points from safety his side looked relegated, but Zaragoza magnificently turned it around to secure their Primera status.
This season things look to be happening in reverse.
No league win in 2013—that's 11 games—has seen them slip to just two points above the trapdoor.
Jose Mourinho's side are in good form on the other hand, arguably the best they've been in all season.
Sandwiched between recent cup successes they have been on a six-game winning streak in La Liga since they lost at Granada at the beginning of February.
Men to Watch
The last time Los Manos won in the league was 2-0 against Athletic Bilbao in December.
That day in San Mames, goalkeeper Roberto had to be at his best ensure he kept his clean sheet.
You get the feeling that if Zaragoza are to shock Madrid this weekend, he'll have to be on form again—providing he's passed fit.
His substitute appearance and goal against Manchester United has seemed to breathe some confidence back into the little Croatian.
Last time out in the 5-2 comeback win against Mallorca the 27-year-old continued his return to form following a tough start to his life in Spain.
He scored and backed the goal up with a sumptuous range of passing—more of the same will be expected in La Romareda.
The two sides met at the Bernabeu back in November and Madrid duly handed out a 4-0 hammering to Zaragoza.
First half goals from Gonzalo Higuain and Angel Di Maria put Los Blancos into a comfortable lead at the break.
Late on in the second half Michael Essien and Luka Modric registered to put an unfair gloss on the scoreline given the level of performance offered by Zaragoza.