The Spaniard feels the visitors will tire in the return leg next week, which will provide Pep Guardiola\'s men with the chances they need if they are to turn the tie around.Former Chelsea and Barcelona full-back Albert Ferrer has admitted he fears for the Blues when they visit Camp Nou in the Champions League semi-final second leg on Tuesday.Ferrer played alongside current Chelsea interim coach Roberto Di Matteo when the Londoners met the Blaugrana in 2000. They won 3-1 at Stamford Bridge but suffered a 5-1 defeat in the second leg.Chelsea take a one-goal advantage to Barcelona after defending stoically for 90 minutes, but Ferrer is worried they will struggle to shut the Spanish champions out again.\"For the opposition, it’s basically impossible to defend and press Barcelona for 90 minutes, so sooner or later, the opposition will drop physically, and a big opportunity for Barcelona will come,\" Ferrer told The Daily Telegraph.\"I believe that Chelsea will do the same tactic [on Tuesday], the same 4-1-4-1, with the lines very close to each other, not leaving space. Gary Cahill was very good at the Bridge, considering he was not a regular.\"Ashley Cole did well. He had help from Ramires, who was very good, and this \'two v one\' worked well against Dani Alves. You usually see Alves going forward 10 to 15 times every half. He didn’t do that at Stamford Bridge. So Chelsea deserve credit. But it’s more difficult to cover all the width of [Camp Nou].\"Alves will get forward and probably put some crosses in. Sooner or later, Chelsea will tire and Barcelona will get their chances to score.\" Didier Drogba scored the only goal on Wednesday night, but was also criticised for spending much of the match on the floor. Ferrer believes the Ivorian was doing whatever he could to give his team-mates respite from the relentless Barca attack.\"In terms of how he played football at the Bridge, Drogba was brilliant,\" he added. \"In terms of how he dived sometimes, OK, obviously you are not used to do that in England.\"It\'s difficult to think of Drogba doing these [diving] things because he is such a big lad. But what Drogba was thinking in those moments was that \'we are basically defending and any time we can put on the clock would be good\'.\"