Out: William Saliba
Arsenal Football Newsletter
But Bukayo Saka, Declan Rice and Riccardo Calafiori have escaped fitness blows.
Arteta had been concerned for the fitness of the quartet after they picked up injuries during Arsenal’s win over Crystal Palace on Sunday.
Saliba was forced to come off at half time, while Calafiori and Rice were both substituted during the second half.
Martinelli was able to finish the game - but he limped down the tunnel following the full-time whistle.
Arsenal are next in action on Wednesday night, when they host Brighton in the fourth round of the Carabao Cup.
And speaking on Tuesday ahead of that game, Arteta said: “[Saliba] is out. We are assessing him. [Martinelli] as well that he is going to be out. We have to do some more tests to learn the extent of the injury.
Asked about Saka, Rice and Calafiori, Arteta confirmed the trio as “fine” and “available.”
Arteta is expected to make changes to his team ahead of this clash with Brighton.
In the last round, when the Gunners travelled to Port Vale, the Arsenal boss made nine changes.
Goalkeeper Kepa Arrizabalaga made his debut in that 2-0 win over Port Vale and he is set to start against Brighton.
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Ben White, Cristhian Mosquera and Myles Lewis-Skelly should all come into the defence, while there could be a full debut for Piero Hincapie, too.
Christian Norgaard and Ethan Nwaneri are likely to come into the midfield. Mikel Merino is an option to start as a striker, if Arteta wants to rest Viktor Gyokeres.
Max Dowman is expected to be in the squad. The 15-year-old got 30 minutes off the bench in the last round at Port Vale.