The Deportivo La Coruna defender believes the Blaugrana overcommit players in attack and says an upset is possible when the two sides meetCarlos Marchena has highlighted a potential chink in Barcelona's armour as his newly-promoted side prepare to take on the Liga leaders on Saturday.
While Tito Vilanova's team are unbeaten in the league and in Europe, their hosts are languishing in the relegation zone.
However, the veteran centre-back insists Barcelona have weaknesses that can be exploited.
"They play with a lot of people in front of the ball and they can suffer because they defend with few players,” Marchena told reporters.
The former Valencia man also claimed that the teams who have enjoyed the best results against the Blaugrana have counterattacked well after soaking up long periods of pressure.
The defender added that he has completely recovered from a case of conjunctivitis.
"I have got much better but my left eye is still a bit closed. My visibility is good, but you need four eyes open against Barca," joked the player capped 69 times by Spain.