The Brazilian was a late withdrawal from Arsenal's starting XI for the third-round tie at Emirates Stadium on Sunday (AEDT), which the Gunners won 2-0 after extra-time, and replaced by Reiss Nelson.

Martinelli has only recently returned from a serious knee injury sustained in June and Arteta said the teenager was in tears when providing an update on his condition after the match.

"I am gutted. I was in my office before the game and one of the coaches came in and told me that Gabi had hurt himself, that he'd twisted his ankle," Arteta said.

"I went to the medical room and he was in tears. He was in a lot of pain and we're going to have to see how he is. It didn't look good. He was in pain so I imagine that we're not going to have good news with him.

"We really want to know what's going on. He's a character and he wants to play the next game. He doesn't care and can handle pain but I don't know. Hopefully there is nothing too serious but to start with, it didn't look too good."

Emile Smith Rowe and Pierre-Emerick Aubameyang were on target in the additional minutes but only after Bernd Leno had made a fine late stop from Andy Carroll to force extra-time.

"We had to be patient," Arteta, who has won all seven of the FA Cup ties he has overseen as Arsenal boss, including last season's final triumph over Chelsea, said. 

"They are a team who are well-organised and make it hard for you. We had the chances I think, very big chances to score much earlier but when you don't do that, the game is open.

"If you don't do that in your box, you need your keeper in a key moment – like it happened after the corner kick on the counter – to save you.

"Bernd did it in a magnificent way and at the end we scored two and deserved to go through."