The home side have only picked up six points from their 13 La Liga matches this season to sit bottom of the table, while champions Barca are currently at the summit with 25 points.
Leganes have finished 17th, 17th and 13th respectively since being promoted to the top flight at the end of the 2015-16 campaign, with last season being seen as a huge success for the club.
It does appear that the Madrid side will struggle to remain in La Liga this term, though, as they have only picked up six points from their opening 13 matches of the 2019-20 campaign to sit rock bottom.
Now under the management of the experienced Mexican Javier Aguirre, Leganes have only won once in the league this season, which came at home to Mallorca at the end of October. Since then, they lost to Real Madrid and Leganes but did manage to pick up a draw at Real Sociedad before the international break.
Whether Leganes remain in the league this season is not going to depend on their results against the bigger clubs, but it is not as if it gets easier after this clash as they then face a trip to Sevilla on December 1.
Aguirre has to find a way to start putting wins on the board, though, otherwise the club could be heading for a return to the Segunda Division for the first time since 2016.
The fact that Barca have lost three La Liga matches this season and are still top of the table is an indication of the inconsistency shown by the top teams in the division this term.
Ernesto Valverde's side have picked up 25 points from their 12 matches to top the table, although they are level on points with second-placed Real Madrid and just one ahead of Atletico Madrid in third.
It seems unlikely that the champions will be running away with the league this season, although it would be a huge surprise if they did not put another victory on the board this weekend.
The Catalan giants recovered from a 3-1 loss at Levante on November 2 by beating Celta Vigo 4-1 before the international break, and Saturday's game is very important considering that three of their next four in the league are against Atletico, Real Sociedad and Real Madrid.
Only a win will do in Madrid on Saturday afternoon, and the Spanish champions will then switch their focus to the Champions League as Borussia Dortmund prepare to make the trip to Camp Nou on Wednesday night.
Leganes form: LLWLLD
Barcelona form: WWWWLW
Ivan Rakitic could also miss out with an Achilles issue, but the likes of Lionel Messi, Luis Suarez and Antoine Griezmann are all fit and should start as the front free despite the presence of Ousmane Dembele.
Leganes possible starting lineup: Cuellar; Rosales, Bustinza, Omeruo, Siovas, Silva; Oscar, Mesa, Ruibal, Arnaiz; Braithwaite
Barcelona possible starting lineup: Ter Stegen; Wague, Lenglet, Pique, Firpo; Arthur, Busquets, De Jong; Griezmann, L Suarez, Messi
We say: Leganes 0-3 Barcelona
Leganes will be the fresher of the two teams considering that a number of Barca players have been away on international duty, but we still expect the visitors to have far too much on the afternoon.