The 19-year-old started a Premier League game for the first time since late January against Sheffield United on Sunday, and netted his first goal for almost 15 months in the Gunners' 3-0 win at Bramall Lane.
But the Brazilian was replaced by midfielder Mohamed Elneny in the 83rd minute after appearing to take a knock to the ankle, leading to concerns he had suffered an injury setback following his long-term knee issue last year.
However, speaking to the club's official website after the game, Martinelli, when asked if he a problem, said: "No, I am alright to play on Thursday.
"I am feeling a bit tired but I'm so happy with the goal and even happier with the victory and the three points.
"I work every single day in training, you need to prepare yourself because when Mikel [Arteta] needs you, you need to be there to play and show something."