Mikel Arteta has said Arsenal are "on alert" to enter the January transfer market as ongoing injury issues deplete his squad.
The Gunners travel to Aston Villa on Saturday sweating over the fitness of Declan Rice and Cristhian Mosquera after they became the latest players to suffer a setback this season.
Arsenal have been without Kai Havertz, Gabriel Jesus, Viktor Gyökeres, Martin Odegaard, Gabriel Magalhães and Noni Madueke among others for prolonged spells this season but remain five points clear at the top of the Premier League.
The club spent more than £250 million ($333.5m) on eight new signings but Arteta hinted there may be more to come if the right situation arose.
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Sources have told ESPN that Elche midfielder Rodrigo Mendoza is one player under consideration.
"We always have to be prepared," said Arteta.
"The moment that we have an option to touch the squad, to improve the squad or to protect the squad, depending on what happens, I think we need to be open for it.
"From what is going to happen from here until the window is closed as well, is football. So, we don't know but we're certainly going to be on alert and we know where the risk can come in terms of the squad and be ready just in case we have to do something."
Both Rice and Mosquera were forced off during Wednesday's 2-0 win over Brentford and Arteta insisted he was unable to confirm whether either player would be fit to play at Villa Park until after Friday's training session. On Mosquera, Arteta said: "That's the one that is more complicated.
But again, we have another test today to see where we are with them."
Arteta repeated his line from Tuesday on William Saliba and Leandro Trossard's availability, suggesting it was a "matter of days" until the pair would be fit.