The Catalan club crashed 3-0 at Villarreal, their worst defeat of the season in any competition, to give a big boost to the confidence of the chasing pack led by arch-rivals Real Madrid.

"It wasn't the best way to start the New Year," said Barca coach Frank Rijkaard, after spending nearly an hour with his players in the dressing room on Monday analysing what went wrong.

"I'm calling on all the players to improve their concentration and raise their game.

"After losing a game like we did last week, the thing is to win well in the following game. We can't think anymore about Villarreal, the world hasn't stopped turning."

Rijkaard will give a rare starting chance to Andres Iniesta, the Spanish under-21 international stepping into the breech left by the suspension to Deco.

Ronaldinho missed training on Wednesday, complaining of lumbar problems, but the World Footballer of the Year was back, albeit tentatively, on Thursday and Rijkaard is monitoring his progress closely.

For their part, Real Sociedad have lost Valery Karpin and Mikel Arteta for their visit to the Nou Camp, the pair going down with an injured right thigh and left knee ligament problems respectively.

Barcelona have 42 points from their 18 games as the league reaches its halfway point over the weekend, and they are assured of taking the unofficial title of 'winter champions'.

Real Madrid and Valencia are back on 35 points, and lie second and third respectively separated by only the number of wins.

After triumphing 3-0 at Atletico in the Madrid derby last Sunday, Real are optimistic that they can keep up the pressure on Barca by beating visitors Real Zaragoza on Sunday.

"Seven points isn't an insurmountable gap. I remember one year when we won the league, we had a lead like that but we ended up having to fight until the last game of the season," said Real goalkeeper Iker Casillas.

However, Real's new coach Wanderley Luxemburgo has worries over the fitness of two of his key players.

Club captain Raul Gonzalez has a tender left hamstring while Ronaldo is suffering from a series of niggles in his left leg, a result of Spanish first division defenders paying constant attention to the Brazilian World Cup winner.

Zaragoza's task of restraining Real will not be helped by the suspension of the Argentine central defender Gabriel Milito, who last season had two outstanding games against the club that signed him and then refused to complete the deal on the pretext of a failed medical test.

If the top two slip up, then Valencia could take advantage.

After a shaky start, Valencia coach Claudio Ranieri has guided the reigning Spanish champions to eight straight unbeaten games and will be looking to extend the streak to nine at Osasuna.

FIXTURES
Saturday (kick off GMT): Getafe v Atletico Madrid (1900), Malaga v Sevilla (2100)

Sunday: Albacete v Racing Santander (1600), Athletic Bilbao v Espanyol (1600), Real Betis v Real Mallorca (1600), Deportivo La Coruna v Numancia (1600), Levante v Villarreal (1600), Osasuna v Valencia (1600), Barcelona v Real Sociedad (1800), Real Madrid v Real Zaragoza (2000)