The Terriers crashed to a 6-1 defeat at the King Power Stadium, prompting the club’s incensed manager to cancel the squad’s day off.
Ahead of today’s FA Cup third-round trip to Charlton Athletic, Grayson said: “We got the players in on Wednesday and had a meeting. We said a few home truths and the players also discussed what happened at Leicester.
“Since then, the players have been excellent in training, but the proof is in the pudding so we can’t say anything about whether the meeting has done the trick until we have played a game.
“But the players know the reaction I want to see. It isn’t just about the result, I want to see a good performance.”
The heavy defeat to Leicester means Huddersfield have not won since November 10, a run of 10 games.
Grayson, whose side drew 1-1 at The Valley in November, added: “It is only six or seven weeks since we were flying high and in the play-offs. We were in the top two not too long ago, either.
“Since then we have slipped and we need to get back to that (earlier) standard of performance.
“We have a good group of honest professionals so I am expecting a reaction. To be fair to them, Leicester wold have given anyone a game on Tuesday.
“They are a good team and were on top form. But, even so, we need to perform better ourselves as that wasn’t good enough from us.
“I am not sure if we’d prefer a league game or the Cup. The main thing is we will be out on the pitch and in a position to put what happened at Leicester firmly behind us.”
Keith Southern is a major doubt today for Town, whose focus after the tie will turn to the transfer window as Grayson looks to strengthen his squad.
The Town manager added: “We sat down recently as a club and identified a few areas where we need to strengthen.
“The problem in January is a lot of clubs are reluctant to let players out. Usually, they have to have a replacement in the building before anyone can leave.
“We understand that as it is how we think. But it also makes things frustrating and not as easy as fans think when it comes to trying to strengthen.
“Adding to the complications is that clubs also won’t let any loan players become cup tied. That has given us a bit of breathing space and always made it more likely that Birmingham in a week’s time would be a more realistic target.”