Martinelli suffered an injury in Tuesday’s 4-1 loss to Manchester City in the Carabao Cup.
The 19-year-old, who only recently returned from a long-term knee injury, collided with city goalkeeper Zach Steffen shortly before half-time.
He came out for the second half but was then substituted minutes after the restart, with head coach Mikel Arteta insisting the move was just a precaution.
Martinelli took to Instagram on Wednesday to reassure Arsenal fans with a message that read: “I feel great and ready to go. ”
Arsenal will then face London rivals Chelsea in the Premier League on Boxing Day.
Redknapp: Arsenal Square the Knights
Jamie Redknapp called Arsenal “a team full of kids” in a scathing denunciation of the Gunners’ current first team.
After a dramatic drop in form, Arsenal failed within four points of the relegation zone and were knocked out of the Carabao Cup on Tuesday night following the loss to City.
But Redknapp dismissed suggestions that Mikel Arteta’s work should be at stake as he expressed contempt for the players available to Arteta.
“Of course you could go and fire the manager, but the biggest problem is that there is a group of players there and there are only three or four that if you were the incoming manager, you’d say I could trust these players, ”Redknapp said.
“That will be the problem with this team. Too many of them, whatever you do, will let you down. It’s a team full of kids at the moment and I’m sorry for the young players. Arsenal need to stick with the manager and give her time to take out a lot of players who are not good enough.
“I keep hearing about trouble in the locker room and someone in the locker room giving information. If you’ve got that, you’re in big trouble.
“You don’t stand a chance. You have to get rid of these players as quickly as possible and it is not easy to do. If you get rid of the manager, who comes in? Who is there? ”