Jack Wilshere and Kieran Gibbs face a race against time to be fit for Arsenal's Champions League clash with Borussia Dortmund as pair continue to recover from respective ankle and calf injuries.
Gibbs featured against Liverpool on Saturday but the left-back came off the pitch in the 78th minute and Arsene Wenger has since confirmed that he has a problem with his calf though the manager is unsure over the extent of the injury.
"Gibbs has a calf problem," the Arsenal boss said. "I don't know exactly how bad it is."
Meanwhile Wilshere rolled his ankle in training on Thursday after featuring in the 2-0 loss to Chelsea in the Capital One Cup and Wenger has admitted he will have to wait to see if the midfielder is fit enough to face Dortmund on Wednesday night.
"I will follow the medical advice," he explained.
"He came in on Friday and was not available. We kept him out of the training. On Saturday he had a session but inside on the bike and we will see on Monday morning how he is."
Jurgen Klopp's men, who defeated Arsenal at the Emirates a fortnight ago, were the surprise package of 2012-13 Champions League, reaching the final only to be beaten by Bayern Munich and this season face a tough test to emerge from their group which also include Napoli.
With three games to go before the sides know who will go through until the next stage Arsenal, Napoli and Dortmund are all level on six points and Wenger's squad still need to play both sides away before the conclusion of the group stages.
Both Wilshere and Gibbs have been improved players for the side this season and have had a hand in taking them from top four contenders to serious title challengers.
And Wenger will certainly be keen to have them on hand on Wednesday though Nacho Monreal is an able replacement in the absence of Gibbs, while Mikel Arteta will remain at the deepest lying midfielder after an injury return.