The home side operate in Spain's fourth tier, and this will be comfortably the biggest game in their 90-year history, while Barcelona will be aiming to progress in a competition that they have won a record 31 times.
Match preview
Barbastro caused a shock in the last round of the Copa del Rey, as they recorded a 1-0 victory over La Liga outfit Almeria, with Franc Carbonell netting the only goal of the contest in the 28th minute.
This is already their best performance in the Copa del Rey in their 90-year history, and Sunday's fixture will be a historic affair for all involved with the football club.
Barbastro are the overwhelming underdogs, but they will enter the game in strong form, winning four of their last five matches in all competitions, remaining unbeaten in the process.
Dani Martinez's side were 1-0 winners over Real Sociedad's third team in their last match on December 16, with the result leaving them in ninth position in Group 2 of the Segunda Division RFEF table.
The Aragon-based outfit have not been beaten since the middle of November, but it remains to be seen whether the recent break has helped them, as Barcelona have a quick turnaround, with Xavi's side in action against Las Palmas in La Liga on Thursday night.
Barcelona fell 1-0 behind to Las Palmas in the 12th minute of the clash, with Munir El Haddadi netting against his former club, but Ferran Torres levelled the scores in the 55th minute, before Ilkay Gundogan struck the winner from the penalty spot in the 93rd minute.
The 2-1 success moved the reigning champions onto 41 points and back into third spot in the table, but they are seven behind leaders Real Madrid and second-placed Girona, so there is hardly any room for dropped points in the second half of the campaign.
Barcelona's attention will quickly switch from the Copa del Rey to the Spanish Super Cup, as they head to Saudi Arabia to take on Osasuna in the semi-finals of the competition on January 11 ahead of a potential final against either Real Madrid or Atletico Madrid three days later.
Blaugrana are the most successful side in the history of the Copa del Rey, winning the competition 31 times, which is eight more than Athletic Bilbao, who are second in the rankings.
Barcelona have not managed to lift the trophy since the 2020-21 campaign, though, and they suffered a 4-0 defeat to Real Madrid in their last match in the competition in April 2023.
Barbastro Copa del Rey form:
W
W
Barbastro form (all competitions):
Barcelona form (all competitions):
L
L
D
W
L
W
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Team News
Barbastro head coach Martinez is likely to select the same side that took to the field for the clash with Almeria in the last round of the competition.
Adria de Mesa is the team's leading goalscorer this season with four, and the 32-year-old is set to lead the line with support from Oscar Gonpi and Hugo Bautista.
Javito is again set to feature in a midfield position for the home side, while Kike Rausell is also likely to be involved from the first whistle against the Spanish champions.
As for Barcelona, Joao Cancelo picked up an MCL strain during the league contest with Las Palmas, so the Portugal international is set for a period on the sidelines.
Pedri, Marcos Alonso, Gavi and Marc-Andre ter Stegen are also still out, while Inigo Martinez is likely to be held back for the Spanish Super Cup, with the defender close to overcoming a muscular problem.
Head coach Xavi will ring the changes for the Copa del Rey contest, with Hector Fort potentially in line for a first-team debut at right-back, while Vitor Roque could make his full debut for the club after featuring off the bench against Las Palmas.
Andreas Christensen, Joao Felix, Lamine Yamal and Fermin Lopez should also be among those to be introduced into the side, while there could be minutes for 16-year-old Pau Cubarsi.
Barbastro possible starting lineup:
Fabrega; Val, Mingotes, Jaime, Carbonell; Javito, Rausell, I Garcia; Bautista, De Mesa, Gonpi
Barcelona possible starting lineup:
Pena; Fort, Christensen, Kounde, Balde; F Lopez, Romeu, Roberto; Yamal, Roque, Felix
We say: Barbastro 0-4 Barcelona
Barbastro were excellent against Almeria in the last round of the competition, but this will be a step up in class, and we are finding it so difficult to predict a shock here. Barcelona head coach Xavi will ring the changes from his usual side, but the Catalan outfit should still have far too much for their fourth-tier opponents.