Real Madrid boss Carlo Ancelotti has admitted that a poor final 30 minutes cost his team in Sunday's 2-1 defeat at Barcelona.
Los Blancos levelled the scores through Cristiano Ronaldo after 31 minutes, before dominating the play either side of the interval.
However, Luis Suarez's 56th-minute effort secured all the points for the home side, who have moved four points clear at the top of La Liga.
"It was a match between two high-quality teams. For our part, I think we did well for an hour, until the second goal. Then the game became complicated," Ancelotti told reporters in Spain.
"In the first half of the game, we did well. We were very solid at the back but we weren't able to be consistent. We played a good hour and not so well for 30 minutes.
"The team has improved a lot but La Liga is complicated. Barca has the advantage in the table but we can't throw in the towel. We need to continue playing like we did in the first half."
Real Madrid have now lost six times in 2015.
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