Mansion Sports – The clash between Athletic Bilbao and Arsenal in the 2025–2026 UEFA Champions League stands out as one of the most eagerly anticipated encounters of the season. 

For the very first time, the two sides will meet in an official competitive match at San Mamés Stadium on Tuesday, September 15, 2025, at 18:45 local time. 

Before the action begins, here is Mansion Sports’ prediction for the lineups of Athletic Bilbao vs Arsenal 2025.

Arsenal’s Burning European Ambition

Arsenal travel to Spain brimming with confidence. Since their return to the Champions League stage, Mikel Arteta’s side has shown consistent progress. 

After reaching the quarterfinals in 2024 and advancing to the semifinals in 2025, the Gunners are now considered one of the leading contenders to lift a trophy that has long eluded them.

Their lengthy absence of European silverware—their last triumph being the 1994 Cup Winners’ Cup—serves as a major source of motivation. 

To strengthen their pursuit, the club invested a massive £250 million during the summer transfer window.

In the Premier League, Arsenal have made a solid start, collecting nine points from their opening four matches. 

Despite being struck by an injury crisis involving Bukayo Saka, William Saliba, Kai Havertz, and Martin Ødegaard, the squad has continued to dominate. 

Their emphatic 3-0 win over Nottingham Forest highlighted the team’s depth, with Martín Zubimendi and Viktor Gyökeres emerging as standout performers.

Adding further intrigue, Arsenal could make history if they defeat Athletic Bilbao. Such a victory would see them become the first team ever to defeat six Spanish clubs consecutively in the Champions League.

Athletic Bilbao Ready for a Special Night at San Mamés

On the other side, Athletic Bilbao enter the contest with renewed spirit. Under Ernesto Valverde, the Basque side finished fourth in La Liga last season, trailing only Barcelona, Real Madrid, and Atlético Madrid. 

This achievement secured their return to the Champions League for just the third time in club history.

Although their previous campaigns in the tournament were underwhelming—failing to progress beyond the group stage in 1998–99 and 2014–15—this year feels different. 

The team is motivated to redeem themselves after their heavy defeat to Manchester United in last season’s Europa League semifinal.

Preparations, however, have not been ideal. After securing three consecutive wins at the start of La Liga, Bilbao suffered a shock loss to Alavés, courtesy of an own goal from Álex Berenguer.

Their situation has been further complicated by the absence of Nico Williams due to injury, alongside unavailable players Aymeric Laporte, Benat Prados, Unai Egiluz, and Yeray Álvarez, who are all serving suspensions.

Nevertheless, the San Mamés faithful continue to pin their hopes on captain Iñaki Williams, supported by the promising midfield duo of Oihan Sancet and Mikel Jauregizar.

Predicted Lineups for Athletic Bilbao vs Arsenal 2025

Athletic Bilbao (4-2-3-1)

• Goalkeeper: Unai Simón
• Defenders: Jesús Areso, Dani Vivian, Aitor Paredes, Yuri Berchiche
• Midfielders: Iñigo de Galarreta, Mikel Jauregizar
• Attacking Midfielders: Iñaki Williams, Oihan Sancet, Álex Berenguer
• Forward: Gorka Guruzeta
• Manager: Ernesto Valverde

Arsenal (4-3-3)

• Goalkeeper: David Raya
• Defenders: Ben White, Cristhian Mosquera, Piero Hincapié, Lewis-Skelly
• Midfielders: Mikel Merino, Martín Zubimendi, Declan Rice
• Forwards: Noni Madueke, Viktor Gyökeres, Gabriel Martinelli
• Manager: Mikel Arteta

Conclusion

This match is far more than just the opening fixture of the Champions League group stage—it is a stage for two clubs with contrasting narratives to prove their worth. 

Arsenal arrive with the ambition of finally conquering Europe, while Athletic Bilbao seek to demonstrate that they can compete at the highest level.

Will Arsenal extend their remarkable record against Spanish sides, or will Bilbao deliver a stunning upset at San Mamés? 

Whatever the outcome, the predicted lineups for Athletic Bilbao vs Arsenal 2025 promise a thrilling spectacle not to be missed.