Raul Jimenez was stretchered off the field in the early stages of Wolves' Premier League match against Arsenal after suffering a head injury.
The striker clashed heads with Arsenal centre-back David Luiz during an aerial challenge in the Wolves box after a corner from Willian.
The incident happened just five minutes into the encounter, but a lengthy delay followed as the players received treatment.
The 29-year-old seemed unresponsive as medical staff checked on him and the Mexico international had to be carried off the field 10 minutes later and was replaced by Fabio Silva.
David Luiz, meanwhile, received treatment for his injury and was able to keep playing, but the Brazilian defender was still bleeding late in the first half.
Jimenez has been a key player for Wolves this season, scoring four goals in nine matches before Sunday's match against the Gunners.
Nuno Espirito Santo's team took the lead at Emirates Stadium after 27 minutes when Leander Dendoncker's header struck the bar and Pedro Neto was there to knock it past Bernd Leno.
Arsenal managed to pull level three minutes later, however, when Gabriel Magalhaes rose to meet a cross from Willian and head past goalkeeper Rui Patricio.
With three minutes left of the first half, Daniel Podence put the visitors back in the lead when Leno parried a Neto shot into the attacking midfielder's path and managed to knock it into the net.
Wolves had won just one of their last four matches in the Premier League heading into Sunday's encounter against Mikel Arteta's men.
Nuno's team were 11th in the table with 14 points before kick-off, seven adrift of leaders Liverpool and Tottenham.
Their north London opponents sat a point behind heading into the match, having collected just four points from their last five matches in the English top flight.