The Terriers are expecting a bumper crowd for the visit of Chris Powell’s side, who have led the division for all but four days of the season.
With Sheffield United not having a game due to Chesterfield’s involvement in the Johnstone’s Paint Trophy final tomorrow and Wednesday travelling to Leyton Orient, Huddersfield have the opportunity to make up ground in the race for a place in the top two.
And Grayson believes a Town win would serve as a huge statement of intent to all the teams chasing promotion, including the runaway leaders.
He said: “Charlton have been very consistent all season long. They have been top more or less from the very start so we know we are in for a big test.
“They play good football and they have a good manager who turned around a lot of players in the summer. He was able to spend some money but spent it well.
“It will be a great atmosphere and we have to try and win the game to help close that gap on the teams above us a bit more.
“As much as people keep telling me Charlton are already up, everyone is still catchable.
“It is a big lead they have but until it is mathematically impossible for them to be caught then I doubt Chris Powell will believe it is over.
“Maybe catching the two teams above us is more realistic. But that doesn’t mean we give up, and a win over Charlton will make a difference.
“Of course, the win is the main thing. We have to focus on what we do and not worry about the others. But a win over a team like Charlton would be a big statement as they have proved themselves so far to be the best team in League One.
“It will raise a few eyebrows at the other clubs, too, as Charlton have proved they are a very good team this season.”
Charlton were the side who ended Town’s record-breaking run of 43 unbeaten games in November with a 2-0 victory at The Valley.
Town, then bossed by Lee Clark, followed that setback with another defeat a week later at home to Bournemouth but Huddersfield have still only lost three league games since the start of last year.
That is one less than Charlton have lost just this season but the Addicks have claimed 24 wins to Town’s 17, which is why the London club will arrive at the Galpharm Stadium a colossal 14 points clear of their hosts.
Huddersfield’s problem has been an inability to close out games once ahead, 24 points having been surrendered from winning positions this season.
On three occasions, the Terriers have squandered two-goal leads while at Bury three weeks ago they managed to let slip a three-goal advantage as the Lancashire side hit back to draw 3-3.
Grayson is unbeaten in his first seven games as manager but Town still trail the second-placed Blades by five points, though the West Yorkshire outfit do have a game in hand.
A 2-0 win at Chesterfield on Tuesday night was a positive start to the final 10-game run-in and the Terriers manager is calling on his players to build on beating the bottom club.
Grayson said: “Tuesday was a big win for us and what pleased me most was the good, professional performance we put in. A clean sheet was just what we wanted as well. It showed the value of remaining focused all the time.
“Chesterfield gave us a good game and probably dominated for the opening 10 minutes. But after that I felt we controlled things well and deserved the win.
“Obviously, we have not gone on to win games in the past when in front at times this season so it was good for the players to close the game out like they did.
“The desire and attitude was spot on. The players wanted to see it through because whatever people say, they are professional and want to do as well as they can.
“In terms of dropping back late in a game, it can become a mental thing sometimes. It is why we stressed to the players the need to keep going forward without being reckless.
“Losing leads like we have has hurt them and no one wants it to happen again. We can’t afford to drop points at this stage of the season, not with so much to play for.
“We had 10 cup finals left before Tuesday and now it is nine.”
Grayson knows all about the qualities needed to prevail in the heat of a League One promotion battle after leading both Blackpool and Leeds United into the second tier.
He added: “The fans can play a big part. I am sure it will be a big crowd and I know from coming here with other clubs just what an intimidating place it can be when the fans are right behind the players.
“The fans have been great since I arrived and I know they will be in fine voice against the league leaders.”
Making up for lost time: Alex Smithies interview, Page 3.