MADRID Jan. 13 (Xinhua) -- FC Barcelona coach Ernesto Valverde will lead his side to their 30th consecutive unbeaten game of the season and beat the unbeaten record of 29 games without defeat previously held by Pep Guardiola if they are able to avoid loss away to Real Sociedad on Sunday evening.

Barca go into the weekend nine points ahead of Atletico Madrid at the top of the Liga Santander (although that could be reduced to six if Atletico win in Eibar on Saturday evening) and assured of the honorary title of 'winter champions' .

That title, however, is not worth anything unless Barca can continue their form in the second half of the campaign, which reaches its midway point this weekend.

Last weekend's 3-0 win at home to Levante and the midweek 5-0 win at home to Celta in the King's Cup implied Barca are slipping into top gear and that is bad news for Real Sociedad.

Although he fielded a strong side with both Leo Messi and Luis Suarez in attack on Thursday, Valverde rested Messi for the last half hour of the game, while he also rested Thomas Vermaelen and Sergi Roberto, both of whom will start in Anoeta, despite the fact that Samuel Umtiti is back in full training after recovering from a torn muscle.

Real Sociedad coach Eusebio Sacristan celebrates his 100th game as coach on Sunday against the club where he was both a player and coach of the Barelona B team. However, he does so at the lowest point in two years at the club with 'La Real' taking just 14 points from their last 15 games and slipping into the bottom half of the table following a good start to the campaign.

Defenders Inigo Martinez, De la Bella and Carlos Martinez are all out through injury, further weakening what has been the Basque side's Achilles heel all season.