While the visitors sit directly below their hosts in ninth position, they also require a win to make up further ground before the end of the season.
Having recorded back-to-back La Liga wins on just three occasions since October, Athletic Bilbao can have few complaints with occupying eighth place heading into the final two games of the campaign.
Furthermore, failing to defeat or score against either Valencia or Granada has left them four points adrift of Villarreal, who occupy the Europa Conference League place.
With Sevilla to come on the final day, Marcelino Garcia Toral's side are clear underdogs to achieve that spot, but the Athletic boss will insist that his players focus on at least trying to stay in the hunt ahead of the trip to Estadio Ramon Sanchez Pizjuan.
Defensively, the Lions have been excellent this season, conceding just 35 times in 36 outings, even if just two clean sheets have been kept in their most 11 matches.
The big issue has been their form away from home, with just four wins being recorded, and playing at San Mames could prove key on Sunday as they attempt to post their 10th victory on familiar territory.
Athletic face opponents in Osasuna who will be more than satisfied with their season thus far, Jagoba Arrasate on the brink of improving on their 11th-placed finish in 2020-21.
Ending the season at home to Mallorca, Arrasate will feel that his team are well set to claim ninth spot, but the carrot of eighth remains a realistic target.
However, Los Rojillos head into this contest on a four-match winless streak, three of those games ending in draws in what Arrasate would have regarded as winnable games.
More disappointingly, Osasuna held leads in all three fixtures, and they will need to rediscover a ruthless streak if they are to extend an unbeaten away record to four contests.
Mikel Vesga was sent off after being introduced as a substitute against Granada and will miss out for Athletic.
With Athletic having failed to score in their last two fixtures, veteran frontman Raul Garcia could also come back into contention.
Arrasate may be prepared to stick with the same Osasuna XI which earned a draw versus Getafe.
Athletic Bilbao possible starting lineup:
Simon; Lekue, Vivian, Martinez, Berchiche; N. Williams, Vencedor, Garcia, Muniain; Berenguer, I. Williams
Osasuna possible starting lineup:
Perez; Vidal, U. Garcia, D. Garcia, Cruz; Torro, Moncayola, Avila, Torres, R. Garcia; K. Garcia
We say: Athletic Bilbao 2-1 Osasuna
Neither team can claim to be in their best form heading into their closing double-header, something which could make for a match mixed with quality and errors. Nevertheless, we feel that home advantage will prove key for Athletic, leading up to predict a narrow victory.