Arsenal are set to be without Martin Ødegaard and Bukayo Saka for their Champions League opener against Athletic Club.
Ødegaard, who was substituted in Arsenal's win against Nottingham Forest with a shoulder injury at the Emirates on Saturday, nor Saka -- absent since he sustained a hamstring problem in his side's victory over Leeds on Aug. 23, took part in training on Monday.
However, William Saliba, who was also sidelined from the win against Forest, is poised to feature after he joined his teammates at the club's London Colney base.
Captain Ødegaard was withdrawn after just 17 minutes on Saturday when he fell awkwardly on his right shoulder following a challenge by Morgan Gibbs-White.
Saka has missed Arsenal's past two matches through injury and, speaking last Friday, manager Mikel Arteta revealed the England international is "trying to get back as quick as possible."
- Summer signings make Arsenal 'more unpredictable' - Arteta
- Strength in depth at last? Zubimendi, Gyökeres spark Arsenal win
- Arsenal's Ødegaard injured again after tackle from teammate
Ernesto Valverde, Athletic's coach, said on Monday that he considers the north London side to be one of the favourites to win the competition.
"Arsenal are totally focused on this match," he said.
"They are one of the favourites to win the Champions League thanks to their technical and tactical ability, and the winning spirit that Arteta has instilled in them.
"It's the start of the Champions League and we're playing against a high-level opponent, the kind that Bilbao likes, but we have to be very careful and take advantage of opportunities. Arsenal won't be forgiving."
Meanwhile, defender Ben White was missing from Arsenal's training session on Monday with a minor issue.
Information from ESPN's Mark Ogden contributed to this report.
