The defending champions turn their attention to league affairs for the first time since their World Club Cup triumph and subsequent mid-season winter break.
Barca were back in action on Wednesday night as they claimed a 4-0 win over Osasuna in the first leg of their Copa del Rey last-16 tie, but in between two early goals from Cesc Fabregas and substitute Lionel Messi's late double they were not always at their best.
And Alves does not expect his side to have it all their own way on Sunday against Espanyol, who sit eighth in the table and went four unbeaten in all competitions before the winter break.
The Brazilian told the Barca website: "The game on Sunday is a difficult one, it's the derby and these types of games are always complicated.
"We'll face the game with ambition. If we play at a high level, they'll have a difficult time too."
By the time they play they could be six points behind leaders Real Madrid, who host Granada on Saturday.
Madrid were far from their best on Tuesday in coming from behind to claim a 3-2 first-leg win over Malaga, but boss Jose Mourinho still say enough to leave him in positive mood.
"I believe we're in good form despite our bad first half," he told his club's website. "That's not to say we think about winning it all.
"For the time being our minds are set on defeating Granada and later on eliminating Malaga. I would have preferred to lose [against Malaga] than to lose our league match on Saturday."
Malaga, meanwhile, face another Madrid side in Atletico, for whom Diego Simeone will take charge of his first match after replacing sacked coach Gregorio Manzano before Christmas.
Also on Saturday, fourth-placed Levante host Real Mallorca, Racing Santander entertain Real Zaragoza and Osasuna go to Real Sociedad.
Sunday's action opens with the lunchtime kick-off between Rayo Vallecano and Sevilla, while Getafe face Athletic Bilbao and Villarreal take on third-placed Valencia.
Jose Francisco Molina will be in control of Villarreal after being placed in charge until the end of the season following the sacking of Juan Carlos Garrido.
Villarreal striker Marco Ruben said: "Matches against Valencia are always good. Both teams will play football.
"It's been a busy week, but we are getting used to it quickly because we look forward to a good start this new phase."
Finally, Sporting Gijon travel to Real Betis.
Real Madrid extended their lead at the top of La Liga to six points with a comfortable win over Granada.
Karim Benzema's 19th-minute strike was levelled by Granada's Mikel Rico after 22 minutes.
However, Sergio Ramos ensured Jose Mourinho's side took the lead again after 34 minutes before Gonzalo Higuain and Benzema extended the home side's advantage within five minutes of the start of the second period.
Cristiano Ronaldo then netted his customary goal and Madrid's fifth two minutes from time as Madrid ran out as comfortable 5-1 victors.
Elsewhere, goals were in considerably shorter supply with just one scored in Saturday's other four games.
Manolo Jimenez made a losing start to his tenure as Real Zaragoza coach as Racing Santander inflicted a narrow defeat on the La Liga strugglers.
Jimenez took over a side rock bottom of the table after the departure from the hotseat of Javier Aguirre, four points behind 19th-placed Racing and five adrift of safety.
Yet it was Racing who gave themselves a shot in the arm at El Sardinero as Bernardo Espinosa's header in first-half injury-time proved enough to earn a welcome victory.
The games between Levante and Real Mallorca, Real Sociedad and Osasuna and Malaga and Atletico Madrid - for whom Diego Simeone was making his debut in the hotseat - all ended goalless.