Martinelli was Arsenal’s sharpest player in the opening 45 minutes as Alexandre Lacazette headed home his cross to equalise for the Gunners – but the Brazilian forward also suffered a worrying injury.
The 19-year-old raced through in an attempt to reach a Joe Willock pass but beaten to the ball by City goalkeeper Zack Steffen and went down in agony.
Martinelli was able to see out the remainder of the half but he looked in discomfort as he hobbled down the tunnel at the interval with the sides level.
Martinelli emerged for the second half but lasted less than three minutes before going down again, this time limping off to be replaced by Nicolas Pepe.
Arsenal went on to lose 4-1 to add insult to injury, though Martinelli has allayed fears he could face another spell on the sidelines.
Martinelli took to Instagram to post a picture of himself from the game with the caption: “Feeling fine and ready to go again.”
The news will be a huge boost to Arteta considering Arsenal’s struggles in front of goal this season, with Martinelli’s positive update suggesting he could be fit to play a part against Chelsea on Boxing Day.
Additional reporting by PA.