With three matches left to play, both sides remain in the running for European football, placing added pressure on Thursday's clash.
Match preview
Since returning to La Liga in 2019, Osasuna have finished between 10th and 11th in three consecutive seasons, but Jagoba Arrasate's men have the chance to improve on mid-table security this time around, as a top-seven finish remains a real possibility.
Trailing seventh-placed Athletic Bilbao by three points, Los Rojillos will move level with the Lions if they triumph on Thursday, although Osasuna's European charge could be hampered by Girona and Sevilla, who are also in pursuit of the top seven.
Arrasate's men head into Thursday's showdown on the back of a 3-0 defeat to Atletico Madrid, meaning that Osasuna have lost four of their last five matches across all competitions, including a 2-1 defeat to Real Madrid in the Copa del Rey final.
That said, the Pamplona outfit have won three of their previous four encounters on home soil, with back-to-back victories over Elche and Real Betis preceding a 3-1 win against Almeria at El Sadar earlier this month.
Despite the fact that only four teams have scored fewer La Liga goals than Osasuna's 32 in 35 matches this term, Los Rojillos have netted eight goals across their past three home wins, proving that they are a force to be reckoned with at El Sadar.
Meanwhile, Athletic Bilbao claimed a 2-1 victory over Celta Vigo last time out, courtesy of goals from Inaki Williams and Alex Berenguer, who ended their side's four-game winless run to lift the Lions back into the top seven.
Athletic's winless run started with a narrow defeat to Sevilla and ended with a 5-1 thrashing at the hands of Villarreal, as braces from Alex Baena and Nicolas Jackson humiliated the Basque outfit at El Madrigal earlier this month.
However, last weekend's triumph means that Athletic have won four of their last eight La Liga clashes, with five victories coming in their previous 10 league outings, so Ernesto Valverde's men will be hopeful of returning to winning ways on Thursday.
It is also worth noting that Athletic Bilbao have lost just one of their last six away games, taking 11 road points from a possible 18 since losing to Atletico Madrid back in February, with three successive away victories coming between March and April.
If the Lions can forget about the recent thrashing at Villarreal and rediscover their best form on the road, they will make life difficult for Osasuna, regardless of Los Rojillos' impressive recent home record.
Osasuna La Liga form:
W
W
L
L
W
L
Osasuna form (all competitions):
W
L
L
L
W
L
Athletic Bilbao La Liga form:
W
L
D
L
L
W
Team News
Osasuna look set to be without Abde Ezzalzouli and Moi Gomez on Thursday after both players missed last weekend's defeat to Atletico Madrid.
With Darko Brasanac (knee) and Nacho Vidal (muscle) also sidelined due to injury, Jagoba Arrasate has a number of selection dilemmas to address as he aims to find a winning formula.
Ante Budimir will continue to lead the line for the hosts, with Lucas Torro anchoring the midfield, while David Garcia and Aridane Hernandez are expected to continue at centre-back.
Athletic Bilbao have multiple injury absentees of their own, with Ander Herrera (muscle), Inigo Martinez (muscle) and Jon Morcillo (collarbone) on the sidelines.
There are also question marks over the fitness of Yeray Alvarez and Dani Garcia, meaning that Ernesto Valverde may opt to start Oier Zarraga in the middle of the park.
Nico Williams will continue to support his brother, Inaki, in attack, while captain and playmaker Iker Muniain will retain his place in attacking midfield alongside Oihan Sancet.
Osasuna possible starting lineup:
Herrera; Pena, Hernandez, Garcia, Sanchez; Moncayola, Torro, Oroz; Garcia, Budimir, Avila
Athletic Bilbao possible starting lineup:
Simon; De Marcos, Vivian, Paredes, Berchiche; Zarraga; Williams, Sancet, Muniain, Berenguer; Williams
We say: Osasuna 1-1 Athletic Bilbao
When you couple Osasuna's strong home form with Athletic Bilbao's impressive away record, all the signs point towards a close-fought battle at El Sadar.