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.
"One day Messi will retire and what I believe is special about him is that others like Maradona who have won world cups have had ups and downs.
"He (Maradona) was not even half as good as Messi when he was at Barca and I think that already for what he has achieved he deserves to be called the best ever."
Madrid maintain their pursuit of Barca at home to Athletic Bilbao this weekend.
Jose Mourinho's side are five points adrift of second-placed Atletico Madrid, who responded to back-to-back defeats in La Liga and the Europa League with a victory over Getafe and now travel to face Granada.
While Atletico have the strength in depth to compete domestically and in Europe, Malaga have started to flag, as they also contest the Champions League.
The south coast club are without a win in three games as they prepare to take on Osasuna and have dropped down to fifth place.
Real Betis have developed a solidity to their game this season, which has helped them up to fourth in the table. But they will now be tested to the limit when they play the hotly contested Andalusian derby with Sevilla.
Levante were left angered by the quality of the refereeing which they felt favoured Real Madrid as they lost to the champions last weekend and now take on struggling Deportivo la Coruna who had five put past them by Zaragoza.
Second-from-bottom Espanyol have a difficult away game against Valencia who have finally clicked into gear under new coach Mauricio Pellegrino.
Elsewhere Celta Vigo tackle Mallorca, Real Sociedad play Rayo Vallecano and Getafe are in action against Valladolid.
Saturday (all GMT)
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