Watford boss Claudio Ranieri apologised to fans after they collapsed 3-0 at home to Norwich City on Friday night.
Josh Sargent struck twice and Adam Idah also scored for the visitors, with Watford striker Emmanuel Dennis being sent off in the second-half.
Ranieri later said: "Before I answer I want to say sorry to our fans because we wanted to do something better. We asked the players to light with fire and we can't lose this match, but after the goal we disappeared.
"Maybe we played better 10 v 11. It is very important the lesson Norwich gave us, they played as a team, we played as individuals. That is no good. Now I have to choose the players that want to fight hard for Watford. You have to play 11 v 11.
"I believe in my reaction and the players' reaction. It is not possible to continue in this way because this way we go straight into the Championship. I want the players with heart and mentality who play for the team.
"I speak every day with the board and we are all together. I believe in these players, the players who want to believe. Who doesn't want to believe - go home.
"The new players played very well had understand my philosophy. Some players don't want to understand my philosophy - I want to play straight away, no dribble dribble, shoot straight away.
"We have to react immediately."