Xavi's side are currently top of the table, nine points clear of second-placed Real Madrid, while Athletic occupy ninth, four points behind sixth-placed Villarreal in the race for European football.
Match preview
Athletic have not actually been victorious since February 11, when they were 2-1 winners at Valencia, losing three of their last four matches in all competitions during a disappointing run of form.
Ernesto Valverde's side have only picked up one point from their last three league matches, losing to Atletico Madrid and Girona before playing out a goalless draw with Rayo Vallecano last weekend.
The Basque outfit also have work to do in their Copa del Rey semi-final, having suffered a 1-0 defeat to Osasuna in their first leg of their last-four affair, with the reverse fixture scheduled for April 4.
Athletic's recent wobble has seen them drop into ninth position in the table, but they are only four points behind sixth-placed Villarreal and will certainly still have their eyes on a European finish.
The Lions have picked up 20 points from their 12 league games at San Mames this season, but they will be welcoming a Barcelona side with the best away record in the division, with Xavi's side picking up 30 points from 12 fixtures courtesy of a record of 10 wins and two defeats.
Barcelona last lost to Athletic in La Liga back in August 2019, and they have won the last two league games between the two sides 4-0, but the points were shared in a 1-1 draw at San Mames last term.
The Catalan outfit's elimination to Manchester United in the Europa League means that they have had a rare free week, with the team last in action against Valencia in La Liga on March 5, when Raphinha's 16th-minute effort proved to be the difference between the two sides at Camp Nou.
Barcelona have already won the Spanish Super Cup this season but are chasing success in two more competitions, including the Copa del Rey, where they lead Real Madrid 1-0 following the first leg of their semi-final, with the second leg set to take place at Camp Nou on April 5.
Xavi's team are also in a strong position at the top of the La Liga table, sitting nine points clear of second-placed Real Madrid, although the gap would be cut to six if Los Blancos beat Espanyol on Saturday afternoon.
Barcelona will actually welcome Real Madrid to Camp Nou in the league next weekend, and a victory in that match would do serious damage to the reigning champions.
Athletic Bilbao La Liga form:
L
W
W
L
L
D
Athletic Bilbao form (all competitions):
W
W
L
L
L
D
Barcelona La Liga form:
W
W
W
W
L
W
Barcelona form (all competitions):
D
W
L
L
W
W
Team News
Athletic will be without the services of Oihan Sancet following his straight red card against Rayo last time out. Unai Simon, Jon Morcillo and Ander Herrera, meanwhile, remain on the sidelines through injury.
Inigo Martinez, who continues to be linked with a switch to Barcelona, has seemingly fully recovered from a troublesome foot problem, with the Spaniard set to retain his spot in defence.
However, there could be a change in midfield, with Mikel Vesga potentially bring introduced, while Inaki Williams and Iker Muniain are also set to return to the starting side for the contest at San Mames.
As for Barcelona, Pedri and Ousmane Dembele are getting closer in terms of their recoveries from hamstring issues, but the pair will again be unavailable for selection here.
Ronald Araujo will also be missing due to the red card that he picked up against Valencia, but two key players are set to return to the starting side for this match.
Indeed, Gavi is available again following a suspension, while leading goalscorer Robert Lewandowski has also recovered from a hamstring issue, with the Poland international set to lead the line.
Sergi Roberto could feature at right-back, while Franck Kessie is expected to return in central midfield, which would lead to Gavi starting further forward for the division leaders.
Athletic Bilbao possible starting lineup:
Agirrezabala; De Marcos, Vivian, I Martinez, Lekue; Zarraga, Vesga; N Williams, Muniain, I Williams; Guruzeta
Barcelona possible starting lineup:
Ter Stegen; Roberto, Kounde, Christensen, Balde; F de Jong, Busquets, Kessie; Raphinha, Lewandowski, Gavi
We say: Athletic Bilbao 1-2 Barcelona
Barcelona should be fresh entering this match, having not been involved in a midweek fixture, while the returns of Gavi and Lewandowski are key for the Catalan side. Athletic are certainly capable of picking up a positive result, but we just have a feeling that the visitors will shade this game on Sunday night.