Lionel Messi has admitted that Barcelona tend to struggle against defensive teams and feels that not having a plan B has cost them in the past.The Catalans have been criticised for their insistence on staying true to their possession-based style of play against teams that opt to sit back and solely focus on defending, and Messi has now acknowledged that Barca could do with an alternative incase their original game-plan fails."Teams that sit back and solely defend tend to cause us problems and have knocked us out in the past," the Argentine told TyC."There have been moments where we paid a heavy price for not having an alternative game-plan. "Think about teams such as Chelsea [in 2011-12] and Jose Mourinho's Inter. AC Milan and Real Madrid also played us in the same way this season."The prolific attacker then went on to stress that Barcelona are missing head coach Tito Vilanova.He added: "The players know each other well and all know how to play, but you need the coach for a lot of details. Of course, we have a lot of respect for Jordi Roura, but Vilanova's absence has been a blow."Tito is a very intelligent guy and knows how to transmit his ideas to the players. He knows his football. He's different to Pep Guardiola."Sporting director Andoni Zubizarreta revealed at the weekend that Vilanova is expected to return to the bench in the near future.