The Foxes enjoyed a perfect start as Ben Chilwell struck in the opening ten minutes, with VAR then awarding Ryan Bertrand a deserved red card. The Foxes doubled their lead through Youri Tielemans as he scored his second goal in as many games, with Ayoze Perez then adding to the scoreline with his first Leicester goal.
He then got his second just before the break as he powered home Chilwell's great cross, with enough time left before half-time for Jamie Vardy to finish off a great team move to give Leicester an unbelievable lead.
Southampton's horrendous showing continued after the break as first Perez sealed his hat-trick, before Vardy headed home another. James Maddison netted a free-kick in the closing stages, with Vardy scoring from the penalty spot in the final second of the match to secure his own treble.
Story of the Match
Early lead for Leicester
In what was a sodden St Mary's Stadium, Leicester seemingly adapted to the conditions the better and stole an early march. Chilwell played a clever pass into Harvey Barnes and the winger attempted to finish into the bottom corner. Angus Gunn could only parry his shot straight into the path of Chilwell, who was waiting only yards out to slot home.
The hosts' night was made even worse only seconds later. With VAR checking the goal and in particular a crunching challenge on Perez by Bertrand, a red card was brandished for the full back.
Two in two minutes for the Foxes
The man advantage paid instant dividends for Leicester as they doubled their lead. Barnes sprinted down the left-flank and tried to cross the ball into the box, with his ball being cut out by Yann Valery. The Frenchman could only play the ball into the path of Tielemans though and he stayed cool to finish confidently into the bottom corner.
Rodgers' troops got another one and all-but wrapped the match minutes later and it was an important strike. Perez drifted in off the right-flank, exchanging passes with Tielemans, before hammering the ball into the near post for his first goal since joining the club.
The goals keep on coming
Like London buses, the Spanish forward then got a second as he ghosted in undetected at the far post to power Chilwell's beautiful cross into the roof of the net.
There was time before the break for Vardy to even get in on the act. He was picked out by Barnes and shimmied away from his defender to then dispatch the ball into the back of the net and polish off a scorching opening period for the visitors.
Two more then came quickly after the break as Perez got his hat-trick. Controlling a great ball from Chilwell on his chest, the former Newcastle United man volleyed in a stunning finish. Then, it was Vardy's turn once again as he got on the end of another cross from Chilwell and with no one to mark him, easily headed home.
Late goals secure record for Leicester
With Maddison not yet on the scoresheet, he did get his goal as he guided a great free-kick into the top corner. Then, Vardy also secured his treble as he was tripped by Jan Bednarek on his route to goal in the penalty area and scored from the resultant spot-kick.
As a result of their wonderful win, Leicester rise to second in the table, whilst the Saints fall to 18th ahead of the weekend's games.
Following even the second or third goals, it could well have been easy for Leicester to take their foot off of the gas. They did completely the opposite though and went for the jugular. Every time Rodgers' men went forward, they looked like they were going to score and in the end, the scoreline could easily have been into double figures. A Premier League record win was more than enough though.
VAR does its job
VAR has really, sometimes justifiably, come in for some severe criticism throughout this season but it worked perfectly for the red card. In the euphoria of the goal, Mike Dean from the control room did well to spot the horrendous challenge and award a deserved red card.
Perez off the mark
It's been quite a long time coming for Ayoze Perez's first Leicester goal but he responded in some style on Friday evening. The Spaniard was electric all evening long, with his three strikes clinical finishes of the upmost quality. His treble will hopefully be the beginning of a stretch of some excellent form at the King Power Stadium.
Whilst Leicester were brilliant, Southampton genuinely were dreadful. The Saints' defensive work was abysmal and was a huge reason as to why they shipped nine. They weren't helped by the early red card but nothing justifies that horrendous performance.