Wolves star Raul Jimenez has been forced off on a stretcher with a head injury after a sickening clash of heads with David Luiz.
Jimenez appeared to be knocked unconscious by the blow, and needed immediate medical attention on the pitch.
After a lengthy delay, the Mexican was taken off on a stretcher while receiving oxygen and replaced by Portuguese wonderkid Fabio Silva.
Jimenez has been taken directly to hospital.
Luiz had blood pouring from his head, but was conscious in the moments after the collision.
The Brazilian has had his head bandaged and after a medical check was allowed to continue playing for Arsenal.
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Reacting to the sickening injury, Gary Lineker tweeted: “Awful looking head injury to Raul Jimenez. Hope it’s not as serious as it appears.”
Meanwhile, Arsenal official Twitter page wrote: “Sending strength and best wishes to Raul.”
Arsenal manager Mikel Arteta spoke out about the challenge of Wolves ahead of Sunday’s contest.
He said: “Obviously it is different and you could see the way they finished the second half in the last game [against Southampton].
“We know we have to be prepared to go against both situations, in the back three formation they have different options to play as well and they are threat in different areas, so we need to get prepared like we always do.
“[It is] a really tough game, they are one of the most organised teams in the league for sure.
“They have been together for a long time, they have shown in big games against big opponents how difficult they can make it so I am expecting a difficult game against a team that dominates almost every aspect of the game I would say. They know exactly what to do.”