It was a crazy opening 20 minutes at the London Stadium, with two goals from Riyad Mahrez and Robert Huth in the opening seven minutes before Manuel Lanzini got one back. Andre Ayew came close to a equaliser but Jamie Vardy made sure of the result with the third goal in the 38th minute.
The second period certainly didn't have the same drama as the first early on but burst into the life, with Ayew getting another back and Andy Carroll having one cleared off the line, before Ayew missed a sitter which saw Slaven Bilic's winless run extended to five.
Early shock to the system
After their historic passage into the last eight of the Champions League midweek, many Foxes were optimistic of continuing their rise back up the league table but none would have expected the start they had.
People were still finding their seats in the 60,000-seater arena when the visitors took the lead, it certainly came from nothing as Mahrez did well to whip his cross into the area. Both Vardy and Shinji Okazaki both couldn't get a touch onto it, but it had Darren Randolph scrambling but he couldn't prevent the cross turned shot creeping into the bottom corner.
It was just seconds later and it was a hammer blow to the home side, Mahrez played a good back and forth before the full-back did well to get the ball into the mixer. It managed to find the head of Huth who did well to nod beyond the reach of Randolph to cap off an excellent start for the Foxes.
Grain of hope
That shock to the system took a while to shake off, but the Hammers picked themselves up and gave themselves some hope in quite some style.
Lanzini had been excellent since the turn of the year and stood up once again, the Argentine lined up the free-kick 20 yards out and it was brilliant as he curled into the top corner giving Kasper Schmeichel no chance.
It was nearly two moments later as Antonio did well to power forward into the area, he slid it into the path of Ayew who had space but Huth was in there to poke it wide.
After a positive spell the Hammers were brought back down to earth with a thud as Leicester effectively ended the contest. It was poor from a defensive point of view as Carroll failed to deal with Mahrez's corner at the near post, it bounced off the shins of Wilfred Ndidi to the feet of Vardy who made no mistake as he struck home from close range.
Another glimpse of hope
Both sides came out for the second period knowing that the match as a contest was pretty much over, but the Hammers did their best to try and get something from the contest as they managed to get another goal back.
It was easy for the Hammers as Lanzini whipped a corner in which found Carroll, the striker did well to knock it back across goal where Ayew is waiting to nod home with help from a Schmeichel deflection.
Trying to snatch it at the end
After that goal the home side had the bit between their teeth, and had two excellent opportunities to grab much needed point.
Carroll couldn't have come any closer in the 77th minute, when Carroll managed to get his head to Ayew's cross. Schmeichel did brilliantly to keep it out at the near post, the Hammers looked for some help from the goal decision system but referee Roger East waved play on.
Bilic will be scratching his head to how his side didn't get a point, with Ayew having a horrible miss with ten minutes to play. Antonio did well to wriggle his way into the area and slide it into the Ghanaian, he was one-on-one with Schmeichel but somehow managed to hit it over the crossbar.