Barcelona coach Tito Vilanova is frustrated by having to reshuffle his defence after Carles Puyol dislocated his elbow against Benfica.
Due to absences at the back, the Catalan outfit have been forced to convert a few players into makeshift centre-backs, with defensive midfielder Javier Mascherano among those deputising.
With Puyol being injured during Tuesday's Champions League win over the Portuguese side, Vilanova will again be forced to make unforeseen changes.
"We are always having problems with central defenders," Vilanova told reporters. "It has forced us to convert some players in terms of position.
"Puyol has now suffered a couple of injuries this season that we might say weren't exactly normal, such as a broken cheekbone, and now a (dislocated) elbow.
"We'll have to wait and see how long he's going to be out for but he'll be an important loss for us."
The 43-year-old Vilanova will be overseeing his second Clasico of the season against Real Madrid on Sunday, and believes the Benfica win stands them in good stead.
"The win took a lot of effort but despite that we took three very important points here in Lisbon. We are very happy with the result," he said.
"Alexis Sanchez is continuing to show he is a player who wants to grow. As we saw with Cesc Fabregas earlier in the season, now is the time for Alexis to push on.
"It will be a tough game against Real Madrid. What we must do now is to recover from these last two matches and start to think about the encounter at the weekend."
Benfica coach Jorge Jesus labelled Barcelona as the world's best team after his side's defeat.
"We were up against the best team in the world, a side that always has 70 percent or more of possession and that dominate all their opponents," he said.
"They have only got the two best players in Europe! We played well in the first half and didn't deserve to be losing at half-time.
"Barca were very effective and that was the difference until they made it 2-0. After that, it was even more difficult."