Real Madrid coach Carlo Ancelotti was pleased with his team's performance against Levante but has warned his players they will need to improve if they are to beat Barcelona next weekend.
Los Blancos warmed up for the encounter at the Nou Camp with a 2-0 home victory over Levante on Sunday.
Gareth Bale scored both goals as Real halted a three-match winless run to move one point adrift of league leaders Barca.
"It was a good first half, we played well, with intensity and quality," Ancelotti told his club's official website. "The tempo dropped off a bit in the second half.
"We lacked penetration. We were brimming with confidence in the first half.
"The second half worries me a little bit. We will take the good first half performance and the win away with us in order to continue improving.
"I think we'll be full of confidence heading to the Camp Nou.
"But it is going to be a different match compared with that of Levante. We need to be at our best, at our best we can win."
Ancelotti's side had gone into Sunday's match looking to make amends for Tuesday's surprising 4-3 defeat at home to Schalke in the Champions League.
"The entire team looked more eager and focused," the Italian tactician said. "Everyone understood what they needed to do.
"We did it for one half of the game but next Sunday we will need to do it for the whole match."
Unlike Barca, who take on Manchester City in the return leg of the Champions League last 16 on Wednesday, Real will have the whole week to prepare for El Clasico.
"We have the chance to train well for the whole week and prepare for the match both physically and tactically," Ancelotti said. "It is an advantage but Barcelona are well used to playing every three days without it causing them problems."
Sunday's game allowed Ancelotti to hand defender Sergio Ramos and midfielder Luka Modric their first starts since the two players recovered from their respective injuries.
"The important thing was confirming that Modric and Sergio were indeed fit," Ancelotti said. "We also avoided picking up any bookings for Isco and Toni Kroos.
"We will travel to the Camp Nou with almost a complete squad available.
"As for the line up, there won't be any surprises as long as I don't lose my mind this week."
Source: PA
