Quique Sanchez Flores says goalkeeper Heurelho Gomes may have suffered a concussion during his side's 3-2 Premier League win at Aston Villa.
The Hornets continued their fine start to life back in the top flight by prevailing against bottom club Villa, with Odion Ighalo scoring his eighth goal of the season to put the Hornets ahead.
Micah Richards equalised but an Alan Hutton own goal made it 2-1 before Troy Deeney secured the points with a header, although Jordan Ayew grabbed a goal back for Villa in the final minute of normal time.
But Watford's fifth Premier League win of the season was marred by a serious-looking injury to Gomes, who was caught by defender Craig Cathcart as he dived to claim a low cross.
Gomes waved his arms in obvious distress and was given oxygen on the pitch before being taken off on a stretcher, with the game delayed by eight minutes as a result.
Flores told Sky Sports: "I hope he is well at the moment, I wait to hear more news.
"He has concussion or something like this."
Flores added that Gomes will have his injury assessed after feeling pain in his neck.
The Spaniard described the result as "amazing" and praised goalscorers Ighalo and Deeney for showing "fight".
Captain Deeney, a boyhood Birmingham City fan, was booked for celebrating his decisive strike in front of the Holte End.
He said: "I slid on my knees, everyone does that, it's football, we get caught up in the emotion.
"I do not think I offended anyone, you should have heard what the crowd were saying to me, but I am thick skinned and can take it and am more interested in taking three points."
Watford's victory sends them up to 11th place in the Premier League, while Villa remain rooted to the bottom and are now seven points from safety.
