Gerardo Martino's men are now just a point behind Primera Division leader Atletico Madrid after a midweek win over Celta but have been rocked by the loss of Victor Valdes.
Espanyol will be out to halt the title ambitions of Barcelona as the club's bitter city rival continues its hunt for a 23rd La Liga crown.
Gerardo Martino's men have recovered emphatically from a surprise 1-0 defeat at Real Valladolid earlier this month, winning three Liga matches on the bounce.
The club has scored 14 goals in the process, following up Sunday's epic 4-3 Clasico success at Real Madrid with a routine 3-0 home win over Celta in midweek to really ignite its title charge.
However, Barca will face a stiff test on Saturday against Espanyol, with the two clubs competing in a bitter rivalry down the years that holds its roots in political differences.
Those differences are less pronounced now, but there is no question of diminishing tensions whenever the two sides meet on the field.
This weekend should be no different, with both sides needing maximum points to aid their respective causes as the La Liga season enters its final throes.
Barca lies second in the table, a point behind Atletico and two clear of Madrid, while the home side is among a cluster of teams aiming for a top-six finish that would see it qualify for the Europa League.
Javier Aguirre's side has been inconsistent in recent weeks, with two wins, two draws and two defeats in the past six matches, although the team was victorious last time out as goals from Sergio Garcia and Pizzi earned a 2-1 win at Malaga on Tuesday.
Barca was rocked on Wednesday by the news that goalkeeper Victor Valdes has played his final game for the club after tearing his anterior cruciate ligament while making a routine save in the first half at Camp Nou.
With the Spain international having already announced he is to leave at the end of the season, it was a sad way to bow out for the keeper, and there were further concerns for Barca when Andres Iniesta was withdrawn at halftime with a niggling thigh injury.
Along with Valdes, Barca will be without Jonathan dos Santos (knee) and Isaac Cuenca (hamstring), while Carles Puyol (knee) remains doubtful.