Real Madrid captain Iker Casillas warns team-mates they must cut Barcelona's lead soon

Iker Casillas: Knows that his side have to take advantage of the Champions League break

Captain Iker Casillas has warned his Real Madrid team-mates they must begin to cut Barcelona's La Liga lead before the winter break if they want to retain their title.

Madrid have slipped 11 points behind their unbeaten Catalan rivals to cast doubt over boss Jose Mourinho's future beyond the end of the season.

Mourinho, who has been booed by sections of the Bernabeu crowd in recent weeks, has responded by guiding his side to a crucial derby victory over Atletico Madrid last weekend before completing their progress to the last 16 of the Champions League in midweek.

The reigning Champions' European duties are now on hold for two months and Casillas believes they must use that time to kickstart their flagging La Liga fortunes.

"We have targets set for the end of the year," the Spain goalkeeper told the club's official website.

"It is perhaps a pity that the distance between us and Atletico in the league, despite having reduced it last weekend, and with Barcelona, is quite big.

"But we have made it through to the next round of the Champions League; between now and February there will be time to prepare.

Speaking about Saturday's match against Valladolid, who have won their past two to sit seventh, Casillas added: "It will be a difficult match. It is a tough ground to visit where the fans are enjoying the team playing in the first division again.

"Valladolid are playing some very good football and come into the match having beaten Sevilla convincingly.

Casillas is set to return to the starting XI after he was one of seven changes for the midweek 4-1 win over Dutch champions Ajax.

Mourinho was able to rest the majority of his defence in that game with Pepe, Sergio Ramos and Alvaro Arbeloa all sitting out.

The only regular, Fabio Coentrao, limped out in the first half with a hamstring problem and with Marcelo already sidelined, Mourinho will be forced into a reshuffle.

Valladolid could be boosted by the returns of Manucho and Marc Valiente from injury.