
The derby clash could not have come at a better time for Espanyol.
They are fourth in La Liga, having won their last four games. Veteran playmaker Ivan de la Pena is injured, but he has not been an important figure in the club's recent revival anyway.
The key figures have been Albert Riera, Luis Garcia and Raul Tamudo, all of whom will probably be be in the Spain squad for Euro 2008.
They were also the stars when Espanyol beat Barca 3-1 at home last season. And it was Tamudo who scored the late goal in the 1-1 draw in the Camp Nou in June - a result which allowed Real Madrid to pip Barca to the title.
Tamudo's crucial goal - and the way he celebrated it, plus the accusations which followed it - has contributed to a worsening of relations between the Catalan clubs.
Espanyol president Daniel Sanchez Llibre has, controversially, refused to organise the traditional pre-match lunch between the directors of the two clubs.
Barca are in third place, with just two points more than Espanyol.
Coach Frank Rijkaard will probably bring Ronaldinho back into the attack, in place of teenager Bojan Krkic, after making the goofy Brazilian sit on the subs' bench for most of Tuesday's 2-2 draw away to Olympique Lyon in the Champions League.
Thierry Henry, absent in Lyon, is struggling to get over his recurrent back problems. Samuel Eto'o is almost fit after three months' out with torn thigh muscles, and could be on the bench on Saturday.
Barca's other injury victims are Deco and Jose Edmilson.
Also on Saturday, Sevilla - on Cloud Nine after beating Arsenal 3-1 on Tuesday - are away to Almeria. The Arsenal win assures Sevilla of a place in the second round of the Champions League.
"Now we have to turn our attention to La Liga", said coach Manolo Jimenez on Wednesday, "because we have dropped many points recently."
Later on Saturday, leaders Real Madrid are coming off a 3-2 Champions League defeat at Germany's Werder Bremen when they host a Racing Santander side unbeaten in five games.
"I'm really looking forward to Saturday," said veteran Santander striker Pedro Munitis. "We are in good form and really have nothing to lose there."
The diminuitive Munitis has always been very motivated for matches against Real, who sold him off cheaply in 2003.
The big game on Sunday sees second-placed Villarreal away to Valladolid. Villarreal are just one point behind Real, and one ahead of Barca.
Later on Sunday fifth-placed Atletico Madrid are away to lowly Betis. A defeat against Atleti would be the final nail in the coffin of hapless Betis coach Hector Cuper.
Another man looking towards Sunday with more trepidation than expectation is Valencia president Juan Soler, with Valencia fans reportedly planning a mass protest during and after the home game against Athletic Bilbao to demand Soler's resignation.
Soler is very much in the eye of the storm after Wednesday's Champions League elimination, thanks to the 0-0 draw against Schalke 04.
Sunday's other games are Getafe-Levante, Recreativo Huelva- Zaragoza, Deportivo Coruna-Osasuna and Mallorca-Murcia.
DPA