Barcelona have only dropped two points so far this season, rolling out victories to open up an eight-point lead over rivals Real Madrid, but defender Gerard Pique admits that they are still vulnerable at the back.
The Catalan side's gung-ho style under new coach Tito Vilanova, which has sometimes left only two in defence as both full-backs surge forward, has led to an average of more than three goals a game, with 36 amassed to date.
But as they prepare to take on Zaragoza on Saturday, Pique expressed concern that they were also conceding goals too easily.
"It has almost been as though they (opponents) score against us every time they attack and I am not sure why but it is something that we need to think over," he said.
"We are also scoring more than last season and so, of course, the more attack-minded you are, the more you risk, but we need to improve at the back."
Barca have leaked 14 goals so far -- the most at this stage of the season in 12 years.
Injuries have been partly to blame, although Pique returned to the centre of defence in last weekend's win over Mallorca and now Carles Puyol is in line for a starting place.
Real Madrid dropped behind after a slow start but have now picked up speed with Cristiano Ronaldo returning to form but Pique believes that Barca are stronger with Lionel Messi.
"I respect those who believe that Cristiano Ronaldo deserves to be European Player of the Year but I live with Leo and he is like an alien and Cristiano would be the best human," he said.
“I was a team-mate of Cristiano's at Manchester (United) and he is a hard worker but alongside Messi he doesn't compare."
Osasuna v Malaga 1500, Valencia v Espanyol 1700, Barcelona v Zaragoza 1900, Real Madrid v Athletic Bilbao 2100
Deportivo la Coruna v Levante 1100, Celta Vigo v Mallorca 1500, Getafe v Valladolid 1650, Granada v Atletico Madrid 1845, Sevilla v Real Betis 2030
Real Sociedad v Rayo Vallecano 2030