Gabriel Martinelli could miss the rest of the season for Arsenal after suffering an injury in training.
The Arsenal striker sustained cartilage injury to his left knee during a training session at London Colney on Sunday, and further assessments and tests will take place this week to discover the extent of the problem.
But football.london understands that the Gunners fear Martinelli will be out for months, which would add to Mikel Arteta's mounting problems after Arsenal's poor start to the resumption of their campaign.
The Gunners were beaten 3-0 by Manchester City in their first fixture before suffering a 2-1 defeat to struggling Brighton on Saturday.
Arteta is already without Granit Xhaka, Pablo Mari and Bernd Leno, who have all picked up injuries in the two matches, and Martinelli's absence will rob the Arsenal boss of one of his key attacking options.
Since joining from Ituano FC last summer, Martinelli has netted an impressive 10 goals from 26 appearances in all competitions.
His performances have seen him linked with numerous clubs across Europe, including Real Madrid, Barcelona and Liverpool.
Arsenal goalkeeper Leno previously predicted that Martinelli would develop into a world-class player because of his mentality.
"He can become a world-class player," Leno told SoccerAM.
"World-class 100 per cent because he has talent, he has quality but I think his biggest strength is his mentality.
"He is working unbelievably. I remember in our bad time when we struggled a lot, he was working so hard.
"He was one of the leaders and at 18 years-old he came from nowhere, nobody knew him before and to play like this, to behave like this is very good to see.
"I think if he keeps going like this he will be an unbelievable player."
