Martinelli was substituted inside the opening 20 minutes after failing to recover from a Moises Caicedo challenge
Arsenal manager Mikel Arteta has claimed it is too early to know the severity of Gabriel Martinelli's injury.
The 21-year-old's ankle appeared to get trapped underneath the sliding leg of the Ecuadorian midfielder and he was therefore unable to continue, with Leandro Trossard brought on to replace him against his former club. Martinelli headed straight down the tunnel after his withdrawal and was then spotted post-match walking round the Emirates turf in a protective boot.
The Brazilian now faces a fight to avoid missing the rest of the season with only two matches remaining against Nottingham Forest and Wolves respectively. Speaking after the match, Arteta offered somewhat of an update on Martinelli's condition, but is unsure how long he could potentially be out for.
"We don’t know," Arteta said. "He’s in a boot at the moment. He was very uncomfortable, and he could not carry on playing. We need to scan him and see the extent of that injury."
Martinelli's injury was just the start of a miserable afternoon for Arsenal with the defeat to the Seagulls all but ending their hopes of lifting the title. Manchester City now need just one win from their remaining three matches after beating Everton 3-0 earlier in the day.