Arsenal are assessing Kai Havertz after the forward suffered an injury scare during their winter training break in Dubai, sources have told ESPN.
The exact nature of the problem is unclear but he is thought to have suffered a muscular injury and will now undergo further tests.
Arsenal returned from their break on Tuesday having flown out last Thursday to utilise a rare weekend without a game after they were knocked out of rhe FA Cup third round on penalties by Manchester United.
Any injury to Havertz would be a major blow to Arsenal, who would be left without a recognised striker with Gabriel Jesus joining Bukayo Saka on the sidelines through injury.
After trying and failing to add a striker in the January transfer window, Arteta labelled Havertz as a genetic "powerhouse" who could lead the line instead.
"I don't know ... it it is a possibility [he could start every game]," Arteta said earlier this month. "Maybe we go through that scenario and he scores another 15 or 18 goals? Can you imagine? That's a good scenario.
"Genetically, he is a powerhouse. He is so well-built. He is a player that anything you ask him, he is happy to do: to run in zone six, to be very robust, to make long distances. His body absorbs everything. And then he really looks after himself.
"When you see the professional, how he lives his life, it is immaculate. He does more than any other player there. That is not a coincidence. And then I think he is so intelligent.
"He knows what is good for him and what is not. We know how to manage him and we believe that when he says something it is for the right reason, not because he wants to avoid something. When something works, don't touch him."
Havertz has 15 goals in 34 games in all competitions this season but has been inconsistent in front of goal in recent weeks.
It will come as a relief that Saka has returned to light training at the Dubai camp following his hamstring injury.
