It's not a visit to the Santiago Bernabeu that is worrying Barcelona coach Luis Enrique. Nor a trip to the Vicente Calderon.
But with his team playing at Real Sociedad on Saturday following two straight Spanish league matches without a victory, Luis Enrique is concerned.
"We are in the situation that we need to show that we are consistent and strong," the Barcelona coach said Friday. "And if we look at the precedents it is clear that there is no other stadium in Spain as difficult for us. I would say that it is the most difficult away match of the season."
Barcelona has not won at Anoeta Stadium in nearly 10 years. The Catalan club's last victory came in the 2006-07 season, before Sociedad spent three years in the second division.
In the last five seasons, Barcelona has lost four and drawn one in San Sebastian.
"Since Real Sociedad returned to the topflight Barcelona hasn't won there, it doesn't matter which manager is in charge, so there is something to this," Luis Enrique said. "A streak that long merits some reflection to evaluate what has happened so we can get to work, because only one thing is certain: It will be a difficult match."
Barcelona leads Atletico Madrid by six points and Real Madrid by seven with seven matches to go, but the defending champions drew at Villarreal nearly three weeks ago and then lost to Real Madrid last weekend.
And against Real Sociedad, Barcelona will be without top scorer Luis Suarez, who is serving a one-match ban for accumulation of yellow cards. That means Lionel Messi and Neymar could be accompanied by youngster Munir El Haddadi in attack, or supported by another midfielder, as they try to protect their lead in the standings.
Managed by former Barcelona player Eusebio Sacristan, Sociedad is in the middle of the table. Last week's victory at Sevilla was its first in six league matches.
Last season, a 1-0 loss at Sociedad in January provoked a crisis at Barcelona. The club fired sports director Andoni Zubizarreta the next day, and Spanish media speculated that Luis Enrique would be the next to go.
But that loss marked a pivotal point for the club, which won 18 of the remaining 21 league matches en route to reclaiming the league title. Barcelona also won the Champions League and the Copa del Rey titles to complete a rare treble of trophies.
"It was a loss like any other," Luis Enrique said of last year's setback. "The only thing we can't do at Anoeta is relax. We have to be focused, competitive, better than they are at keeping the ball and at pressuring in defense. We have to do a lot of things better to win there."