Real Madrid's chances of El Clasico success will be heavily influenced by whether captain Sergio Ramos plays, according to Barcelona coach Ronald Koeman.
The first Clasico of the season takes place at Camp Nou on Saturday with the two teams not in vintage form.
Madrid have suffered back-to-back losses against Cadiz and Shakhtar Donetsk, piling the pressure on coach Zinedine Zidane. Barca, meanwhile, lost at Getafe in their previous La Liga outing and continue to deal with off-field turbulence after the Lionel Messi saga in the transfer window and a debate over wages with the club's players.
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Ramos suffered a knee injury in the Cadiz defeat and Madrid struggled without him in Wednesday's 3-2 home Champions League loss to Shakhtar.
Koeman is expecting a more compact Madrid regardless of whether Ramos - who is set to return to the squad - is fit to play from the start, but acknowledges the Spain international will have a big impact if available.
"I am sure they are not going to leave the spaces they have left in recent games," Koeman said at his pre-match news conference.
"We are going to expect a more compact Madrid, with fewer spaces and, for them, it is important that Ramos is there. He is one of the best centre-backs and has a great personality on the pitch. Ramos can influence Madrid on Saturday."
Facing an out-of-sorts Madrid will boost Koeman, given Barca have failed to score in their last two league Clasicos. A failure to net again would equal their worst-ever run, previously recorded in 1958.
Asked about Madrid's struggles, Koeman added: "First, we have to prepare ourselves. They have quality on the ball.
"Like any team and coach, when you make mistakes you want to improve, but neither they nor we will be lacking in motivation. Their players have experience at a high level. I don't expect a vulnerable Madrid, on the contrary."
Jordi Alba is back in Barca's matchday squad after suffering a thigh injury against Sevilla on October 4.
Asked if the defender can start, Koeman said: "The player always has the last word. He knows if he is fit to play or not. I also have to speak to the medical team so we are going to wait.
"I see everything very positively but you have to wait if there is a reaction [in training]. Yes or no. If not, he has a good chance of playing."
The Clasico will also see Lionel Messi look to end his second-longest goalscoring drought in the fixture. He has not netted in 425 minutes of Clasico action, with his last 16 shots against Madrid not being converted.
Messi is, however, the top scorer in Clasico history with 26 goals and also has the most goals in Clasico league meetings at Camp Nou (seven).