Pep Guardiola's side, chasing a fourth straight domestic league title, are three points behind leaders Real Madrid after 16 games despite humbling their rivals 3-1 in the capital last month.
While Barca are unbeaten at home, where they have won eight and drawn one and scored 39 goals without reply, they have won only three of their seven away games, netting 11 and conceding eight, and suffered a surprise 1-0 reverse at Getafe in November, their only defeat of the campaign.
Guardiola told a news conference after Wednesday's 4-0 King's Cup home win over Osasuna he expected a "difficult and physically tough" challenge in the Catalan derby at Espanyol's Cornella-El Prat arena.
Barca have won only two of their last five away games against their neighbours, although they inflicted a 5-1 drubbing on Mauricio Pochettino's team when they visited last season.
"Espanyol have been doing things very well for many years now," Guardiola said.
"They have an excellent coach, they can count on the aggression of young players and they can play good football.
"What we have to do is recuperate well because it's a vital game for the future of our league challenge."
MOURINHO ROCKET
Real Madrid have question marks over the fitness of winger Angel di Maria and defender Sergio Ramos ahead of their game at home to promoted Granada on Saturday.
Both missed Tuesday's comeback cup win over Malaga through injury and the absence of Ramos, who has switched from right-back into central defence this season, was particularly obvious as the home side conceded twice from corners to fall two goals behind by half-time.
A verbal rocket from coach Jose Mourinho at the break and the introduction of Karim Benzema lifted the players, however, and the France striker sealed a 3-2 win with a well-taken goal.
Valencia have done well to keep pace with the big two during the first half of the season and are four points behind Barca in third ahead of Sunday's game at struggling Villarreal.
Valencia's less illustrious city rivals Levante, this year's surprise package, are four points further back in fourth and host Real Mallorca on Saturday.
Hopes are high at Atletico Madrid that new coach Diego Simeone will help the capital's second club find the consistency that will secure them a berth in European competition next season.
Argentine Simeone, a former Atletico player known for his tough tackling and commitment, replaced the sacked Gregorio Manzano last month and makes his debut at ambitious Qatar-owned Malaga on Saturday.
An erratic campaign has left Atletico in 10th place and they have lost seven of their 16 games and conceded four more goals than they have scored.
"We are all very pleased with the new coach and we are working very intensely and very hard," midfielder Juanfran
