La Rojiblancos currently sit six points adrift of the league leaders, but could close that gap to three for a few hours at least with a victory over Barca's local rivals.
While much of the attention is focused on events at the top of La Liga at the moment, Espanyol will still be looking over their shoulders in the closing stages of the season.
Constantin Galca's side will be breathing a lot easier now than they were just a couple of months ago, though, having strung together their best run of form this season right when they needed it most.
Espanyol looked to be in trouble when a 2-1 defeat to Valencia on February 13 left them winless in 10 games in all competitions and with just two points from the last 24 available in La Liga.
However, they have lost just once in seven matches since, picking up four victories in that time to drag themselves eight points clear of the bottom three with only seven games of the season remaining.
They have alternated between victories and draws in their last four games and, should that trend continue this weekend, then they would make it three consecutive home league wins for the first time in more than three years.
It is their home form that has been their saving grace this season, with 25 of their 36 points coming in front of their own fans and only seven teams in the league boasting a better record.
Despite that, Espanyol have averaged just a goal per game from their 15 outings at the RCDE Stadium this season, making them the second-lowest scorers at home in the division behind Real Betis.
Home and away only three teams have scored fewer in the league, which doesn't bode well against a defence as mean at Atletico's, while only Rayo Vallecano have conceded more goals in La Liga this season.
It is a record that has slowly been improving during Espanyol's upturn in form, but with six of their final seven games coming against teams above them in the table, they will need to keep that form up if they are to stay at arm's length of danger.
Recent form: WLWDWD
There were many who questioned whether Atletico had the staying power after they surprisingly won the league title in 2014, but they have shown this year that they are very much one of the big boys in Spanish football now.
Their style is different to that of Barcelona and Real Madrid, with Atletico having scored 36 and 38 goals fewer than those two sides respectively, instead focusing on a tight defensive unit that rarely gives anything away.
They have conceded just 15 goals from their 31 league matches this season - 11 fewer than the next best record in the division, which is held by Barcelona.
It is Barcelona that Atletico must track down in the closing stages of the campaign, and Saturday's match gives them a good chance to put pressure on Luis Enrique's side.
A victory at the RCDE Stadium will close the gap to just three points at the top of the table for a few hours at least, with Barcelona taking on Real Sociedad later in the day at a ground where they haven't won since 2007.
A comprehensive 5-1 victory over Real Betis saw Atletico close the gap last weekend too, helped by Barca's El Clasico defeat to Real Madrid, as Diego Simeone's side made it five wins from their last six games in La Liga.
It looked like they could be on course for unexpected success in Europe too when Fernando Torres gave them the lead at Camp Nou after 25 minutes of their Champions League quarter-final first leg against Barcelona on Tuesday night.
However, the striker then picked up two yellow cards in the space of six first-half minutes to leave his side with an uphill struggle, and sure enough a brace from Luis Suarez saw Barca come from behind to pick up a 2-1 victory.
That is by no means a bad result for Atletico, though, and they will welcome Enrique's side to the Vicente Calderon on Wednesday still very much in the tie and with an away goal to take advantage of.
They have now lost their last two away games in all competitions, but no team have amassed more points on the road in La Liga this season than Atleti, who have won 11 of their 16 away outings.
Recent form: WWWWLW
Recent form (all competitions): WWDLWL
Simeone may opt to make changes ahead of Wednesday's clash with Barcelona, but Torres is suspended for that match and so should feature this weekend.
Espanyol, meanwhile, will be without Arbilla once again, and Galca could name an unchanged side to the one that drew 1-1 with Malaga at the weekend.
Espanyol possible starting lineup:
P Lopez; J Lopez, Gonzalez, Roco, R Duarte; Asensio, Sanchez, O Duarte, Diop, Abraham; Moreno
Atletico possible starting lineup:
Oblak; Juanfran, Hernandez, Godin, Luis; Saul, Gabi, Koke; Partey, Torres, Carrasco
Head To Head
Espanyol have won just one of the last eight meetings between these two sides, with that coming in October 2013 courtesy of a 1-0 victory.
That is the only goal that they have scored in the last seven clashes between the two sides, though, with Atletico keeping six clean sheets in that time, including in each of the last four meetings.
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We say: Espanyol 0-2 Atletico Madrid
With Espanyol's poor goalscoring record this season, particularly at home, and Atletico's defensive stability, it is hard to see the hosts even scoring in this match, yet alone winning it. It should be a typical Atletico victory, and one that closes the gap on Barcelona to just three points.