The 2016 champions will be demoted should they fail to take maximum points on Sunday - and results elsewhere could condemn still them to the drop anyway. The Hammers, meanwhile, may have one eye on an upcoming European final.
Match preview
While the verdict was out as to whether Leicester's goalless draw at Newcastle United on Monday represented a good result in their precarious circumstances, the point Dean Smith's side took home from St James' Park leaves them with hope of top-flight survival.
Holding a Champions League-chasing side on home turf may build a little confidence in the camp following back-to-back losses for the concession of eight goals, but the Foxes' fate is not in their own hands heading into the final 90 minutes of a dismal campaign.
Failure to win this weekend will see the Midlands club relegated from the Premier League just seven years after claiming the title under Claudio Ranieri, and they would become only the second side demoted from the division after winning it - following in the footsteps of Blackburn Rovers.
Only a win over West Ham allied to Everton dropping points against Bournemouth would now see City survive, so Smith's message will be clear ahead of kickoff at the King Power.
Neither form nor precedent bode well, though, as Leicester have won just two of their last 12 home fixtures - losing eight times in the process - while failing to keep a single clean sheet. Furthermore, they have won their final league game in just one of the last seven seasons.
However, one of only four away wins this term came in November's reverse fixture, when James Maddison and Harvey Barnes - who were both controversially dropped against Newcastle - scored for the Foxes in a 2-0 win at London Stadium. A repeat result now could be invaluable.
While West Ham's Premier League season reaches its conclusion on Sunday, they are still over a week away from contesting the Europa Conference League final in Prague, where Fiorentina will stand in the way of some elusive silverware.
The Hammers have not won a major trophy since the FA Cup of 1980, so they could be forgiven for being distracted by such an opportunity appearing on the horizon - yet that did not seem to be the case last Sunday.
Their top-flight safety was assured with a 3-1 win over Leeds United - when Declan Rice most likely signed off his spell in East London by opening the scoring - and the capital club now aim to build more momentum by ending a below-par league campaign with a three-match winning run.
Victory in Leicester could see David Moyes and co climb to 13th in the final Premier League table, which would add a gloss of respectability to a season scarred by several months spent battling at the bottom.
Against the odds, Moyes has survived until the final day when all around him were being fired by trigger-happy chairmen, and as West Ham have lost their final league game just once in the last six seasons he will now seek a similarly positive outcome on Sunday.
Leicester City Premier League form:
W
D
D
L
L
D
West Ham United Premier League form:
L
L
L
W
L
W
West Ham United form (all competitions):
L
W
W
L
W
W
Team News
As Caglar Soyuncu will not be available for Leicester's crucial final-day contest, the Turkish defender has surely played his final game for the club - he is out of contract in the summer and has long been tipped for a move away.
In better news for Dean Smith, midfield regular Kiernan Dewsbury-Hall is back in the fold after missing two matches with an ankle injury, while Kelechi Iheanacho, Ricardo Pereira and Jonny Evans have all overcome knocks to make themselves available for the Foxes' date with destiny.
Wilfred Ndidi is still a major doubt due to a hamstring problem, though, and James Justin, Jannik Vestergaard, Ryan Bertrand and goalkeeper Danny Ward are all sidelined.
After beginning Monday's clash with Newcastle on the bench, both James Maddison and Harvey Barnes should return to the hosts' starting XI as they revert to a four-man defence.
Meanwhile, David Moyes will have Nayef Aguerd at his disposal again after the defender missed last week's win over Leeds with a dead leg; leaving only one man consigned to the West Ham treatment room.
Italy striker Gianluca Scamacca - recently linked with a loan move back to Serie A in the summer - has undergone knee surgery, but the visitors should otherwise have a full squad to choose from.
With plenty of time to recover before the Conference League final, Moyes is set to name a strong side on Sunday, so Michail Antonio could return up front, with Danny Ings making way.
Leicester City possible starting lineup:
Iversen; Pereira, Evans, Souttar, Castagne; Soumare, Tielemans; Tete, Maddison, Barnes; Vardy
West Ham United possible starting lineup:
Fabianski; Coufal, Aguerd, Ogbonna, Emerson; Soucek, Rice; Bowen, Paqueta, Cornet; Antonio