BARCELONA, Spain (AP) -- Still recovering from a morale-busting loss at home in the Spanish league, Barcelona will need to quickly regroup to beat Chelsea and overturn a first leg deficit in the Champions League semifinals today. The defending champions in both Spain and Europe lost to Real Madrid 2-1 on Saturday and now trail their biggest rivals by seven points with four games to go. Last week, the Catalan team lost at Chelsea 1-0 in the first leg of the Champions League semifinals. Barcelona could lose three straight matches for the first time since 2009, tainting a season in which it has already won the Spanish Super Cup, European Super Cup and Club World Cup. The team is also in the Copa del Rey final against Athletic Bilbao. Chelsea is unbeaten in its last six meetings with Barcelona, and the English team will likely keep to its defensive tactics in an attempt to stop Lionel Messi from influencing the match. "I think we'll require (a game) similar to the home leg," Chelsea defender Gary Cahill said after his team's 0-0 draw with Arsenal on Saturday. "A little element of luck, defensively as a whole unit everyone sticking to their task, and the (same) concentration level." Messi was bottled up by both Chelsea and Madrid to remain scoreless in his last two outings, and when he did manage to set up his teammates, they failed to finish. Against Madrid, the three-time world player of the year didn't even manage a shot on goal, something almost unimaginable for the club's all-time leading scorer who already has 63 goals this season. But Messi's absence from practice on Sunday added to the theory that he is among a number of players feeling the strain of another long season. While Barcelona generated more than enough chances against Chelsea to draw or even win the first leg, it was uncharacteristically sluggish and predictable against Madrid with playmakers Andres Iniesta and Xavi not their usual sharp selves. Barcelona coach Pep Guardiola can count on Cesc Fabregas and Pique to be fresh after neither played a minute against Madrid. Pique could play a critical role by starting Barcelona's attacks with his long passing from the back. Interim Chelsea manager Roberto Di Matteo defended his strategy of using two tight defensive lines. Chelsea arrives in better physical form after resting most of its starters over the weekend. Striker Didier Drogba, who scored from Chelsea's only shot on goal in the first leg, is the team's only major doubt as he tries to recover from a knee injury. The winner will face either Bayern Munich or Madrid in the final on May 19. Madrid hosts the German side on Wednesday looking to come back from a 2-1 loss in the first leg.