On what is bound to be a highly charged, emotional day, manager Dean Smith has urged the players and supporters to stick together regardless of what is going on elsewhere.
On the role that the supporters will play during the game, Dean Smith said: "They can make a massive impact on how we play and what they do. We need their support to be one hundred percent behind the players. The only way we will do this is by being all together.
"We all have a responsibility for Leicester City, whether you are employed by the club or support the club. We can win if we are in this together."
Playing the game
With three games all kicking off at the same time to decide the relegation battle, Leicester boss Dean Smith recognises how important it is for his side to stay calm and focus on their jobs which is to win the game.
Smith acknowledges that the situation is relatively simple for The Foxes with them needing to make sure they beat The Hammers before they can worry about results elsewhere.
On the game plan and dealing with the situation, Smith said: "I have been passing onto the players what to expect and how to deal with expectations.
"We have international footballers. They are experienced and they understand the pressure. I have to give clarity on tactics and let them execute the plan.
"We can only control what we do. The players need to control their performance and help their team mates out. It is a simple message really, and the players have trained well so far.
"We have got to win the game, plain and simple. We have to work out a balance and not give big chances away. After a tough first half of the season, West Ham have climbed away from danger and have a good manager.
"We have to have good discipline defensively. We have got creative players that can create opportunities and score goals. We have to make sure we are a good team because West Ham can be hurtful."
Reflections on Newcastle
While it is unlikely that Leicester will stay up, their chances were bolstered on Monday thanks to a solid point away at Newcastle. But despite the point, Leicester boss Dean Smith came under fire for the lack of any attacking play from his side and in his press conference, Smith addressed the issue.
"My biggest problem is that we looked like we were playing for the draw," said Dean Smith. "We kept it tight, but never retained the ball well enough. People have said that we were lucky in that game but I would flip it and say that they were lucky in that game."
Availability for Sunday
Leicester have been dealt a blow ahead of their relegation decider on Sunday with defender Caglar Soyuncu ruled out with a hamstring injury.
There is also a doubt over midfielder Wilfred Ndidi who has a hamstring issue but there is better news on Kelechi Iheanacho, Keirnan Dewsbury-Hall, Ricardo Pereira and Jonny Evans who are all available to play.
Dean Smith said: "Cags [Soyuncu] tried to get back into training yesterday but felt it and it is too close. But he wanted to push himself so that shows a lot about his character.
"Dewsbury-Hall is good. He has been training the last few days. He is available for selection.
"Iheanacho is fine, Jonny Evans is fine and Ricardo, we scanned him and he is fine. Wilf [Ndidi] is the only question mark at the moment. He has not trained yet since the injury."