Wolves striker Raul Jimenez is conscious in hospital and speaking after a clash of heads during his side's Premier League win at Arsenal.
Sunday's match at Emirates Stadium was in its early stages when Jimenez and Gunners defender David Luiz accidently collided at an Arsenal corner.
Jimenez, 29, was given oxygen on the pitch before being taken to hospital.
"You start hearing 'code red'. It was a bad moment for everybody," said Wolves boss Nuno Espirito Santo.
"What was the reaction? Panic, panic panic. You could see the faces on the team-mates. It was a serious situation. It's awful and terrible."
Play was stopped for about 10 minutes while Mexico international Jimenez and Brazil centre-back Luiz received treatment.
Luiz, 33, played on with a bandage wrapped around his head before being substituted at half-time.Wolves climb to sixth with rare win at Arsenal
Nuno said Jimenez was having a scan and added: "He speaks, he's aware. We have to have a proper assessment. He's in good hands."
Jimenez, who was carried off the pitch on a stretcher, scored 17 goals as Wolves finished seventh in the Premier League last season.
He had netted four times in nine top-flight appearances this term before Sunday's match and signed a new four-year contract with the Molineux club in October.
'It's something you never want to see' - what they said
Wolves captain Conor Coady: "We were massively worried when it happened. We knew straight away it was a horrible clash of heads.
"But we just hope and pray everything is OK because it's something we never want to see.
"He is with the right people now and that's the most important thing. He is in hospital and, by all accounts, he is awake and breathing."
Wolves forward Pedro Neto: "I was a little bit worried. I didn't see the impact but I heard it. I hope he is OK and can recover to come back with us."
Arsenal midfielder Joe Willock: "On behalf of the club and myself, we give our best regards to Raul Jimenez. We hope he recovers well. It was a bad incident. David Luiz has recovered well. He looked good when I saw him in dressing room."
Luiz decision raises concussion questions
Arsenal said protocols were followed regarding the decision to allow Luiz to play on after the incident.
However, the Brazilian was pictured with blood seeping from his head bandage and did not reappear for the start of the second half as he was was replaced by Rob Holding.
Footballers who sustain a suspected concussion, either during training or in a game, should immediately be removed from the pitch and not allowed to return until the appropriate treatment has been administered, according to FA guidelines.Arsenal said protocols were followed regarding David Luiz returning to play on
Arsenal boss Mikel Arteta said afterwards: "We followed the protocol to check he [Luiz] had not lost any consciousness, which he hadn't, and then some tests.
"They will continue to do some more checks on him. He was really uncomfortable and couldn't really head the ball and couldn't continue."