Back-to-back defeats by reigning champions Manchester City and runaway leaders Liverpool either side of Christmas dealt an almost certainly fatal blow to Leicester's title aspirations.
The Foxes are actually two points better off now than at this stage of their remarkable 2015-16 title win, but the imperious form of Jurgen Klopp's side makes a repeat triumph even more improbable.
However, this victory, four days after the win at West Ham, keeps the Foxes at least notionally in the hunt, restores the sense of supreme confidence that existed prior to the trip to the Etihad and sets them up for what is a crucial seven days in their season.
On Saturday they face Wigan in the FA Cup third round, followed four days later by the home first leg of their Carabao Cup semi-final with Aston Villa.
Brendan Rodgers took the opportunity to rest a host of players for the game at London Stadium, correctly trusting in a talented second string to get the job done against a woefully poor Hammers side in the death rattle of Manuel Pellegrini's managerial reign.
He was further rewarded for this decision - and the one to switch to a back three, with Ben Chilwell and Ricardo Pereira as wing-backs - at St James' Park with a display full of energy and, once they had a cast-iron grip on the encounter, sensible game management.
Such was the efficiency of their display they did not miss Vardy, who recently welcomed the birth of a daughter. Perez was full of clever running and ruthless against his former side, while Maddison and his replacement Choudhury brought their shooting boots and then some.
Choudhury's strike, in particular, added insult to injury as it was his tackle in a meeting between the sides in August that resulted in the serious injury that keeps Matt Ritchie out to this day.
Newcastle United have lost three Premier League games in a row for the first time since October 2018 under Rafael Benitez.
Where to even start with Newcastle?
In defiance of some of the doom-mongering that greeted Steve Bruce's appointment as Rafael Benitez's successor in the summer, the Magpies have enjoyed a solid season so far - unspectacular but resilient.
This all came undone, though, during a 90 minutes strewn with errors and misfortune.
Joelinton has failed miserably to endear himself to the Toon Army during the first half of the season and only further blotted his copybook with two awful misses - the first the more crucial, coming with the score 0-0 and seeing him head a follow-up to his own blocked shot away from rather than towards the goal.
The second, later in the game, saw him slice a clear shot on goal following a pull-back from the byeline.
It was in defence that the wheels really came off, however, with Lejeune playing a key and calamitous role in both of Leicester's first two goals.
The injuries to his fellow defenders Willems and Manquillo gave Bruce one final role of the dice with his replacements, which he used at the break to usher Sean Longstaff into the game in place of Shelvey, who was also injured.
When Schar then pulled a thigh muscle, he limped out the game and took any hope Newcastle had of getting back into the game with him.