A game of two halves is the only way to describe this season opener.
The Swans attacked with fluidity and defended gallantly during the first-half in which they took the lead through a bullet Ashley Williams header from Mark Gower's corner.
And lady luck looked to have been on the visitors' side when Dorus de Vries saved a Steve Howard penalty early in the second period - the first spot-kick he'd saved in a competitive Swansea City fixture.
That's as good as it got, Leicester turning the game completely on its head with two quick fire goals from substitutes Martyn Waghorn and Dany N'Guessan to inflict a disappointing opening day loss on the Swans.
Paulo Sousa kept the same eleven that started last Saturday's comfortable friendly win over Kilmarnock.
Hat-trick hero Mark Gower occupied one of the wings while Shaun MacDonald was favoured in midfield ahead of new signing Jordi Lopez.
Fellow new boy Stephen Dobbie was named amongst the substitutes alongside youngsters David Cornell, Jazz Richards, Casey Thomas and Chad Bond.
The home side included a fit again Matty Fryatt in attack and Wales Under-21 starlet Andy King in midfield.
Leicester: Chris Weale, Michael Morrison, Wayne Brown, Matt Oakley (C), Steve Howard, Andy King (Dany N'Guessan, 46'), Lloyd Dyer (Nicky Adams, 79'), Matty Fryatt (Martyn Waghorn, 46'), Bruno Berner, Richie Wellens, Jack Hobbs.
Not Used: Conrad Logan (GK), Max Gradel, Luke O'Neill, Paul Dickov.
Swans: Dorus de Vries; Angel Range (Stephen Dobbie, 76'l, Garry Monk(C), Alan Tate; Leon Britton, Joe Allen (Jordi Lopez, 26'), Shaun MacDonald (Andrea Orlandi, 63'), Nathan Dyer, Mark Gower; Gorka Pintado.
Not Used:David Cornell (GK), Jazz Richards, Albert Serran, Chad Bond.
Attendance: 26,171 Away: 3,136
Referee: Grant Hegley (Hertfordshire)
The atmosphere inside this impressive arena was electric as the two teams made their way to the centre of the pitch before the start of the new season opener.
A minutes applause was was held in respect for the late Sir Bobby Robson and, just after 3.05, referee Grant Hegley got this clash underway.
The home side kicked things off and immediately charged forward as they attacked the end behind the goal full to the brim with Leicester supporters.
Last seasons top-scorer, Matty Fryatt, attempted to latch on to the end of a long ball forward which was easily dealt with by Dorus de Vries, but the first real chance fell to the visitors.
Nathan Dyer was clattered midway inside the Leicester half and as no advantage was played Mr. Hegley duly blew up and awarded a free-kick.
But Mark Gower's set-piece fell short and was cleared back to the winger whose second attempt flew high over Chris Weale's goal.
Joe Allen made a fool of Richie Wellens five minutes in as he turned the midfielder on the touchline before feeding Gorka Pintado, only for the striker to lose possession.
The best chance of the early exchanges fell to the home side with 10 minutes on the clock, Wellens picking out skipper Matt Oakley on the right, his low cross was met by a thunderous volley by Lloyd Dyer but, fortunately, Garry Monk put his body on the line to block the shot.
Shaun MacDonald found space only to fire a weak shot low into Weale's path while Leicester striker Steve Howard shot well over the top moments later during a frantic period of end-to-end football.
And as we passed the quarter of an hour mark a moment of magic in midfield by Dyer saw the winger pick out Pintado, he lost out to Wayne Brown who cleared to the path of Angel Rangel whose strike was cleared for a corner.
And it was from the resulting flag-kick that brought the opening goal of the game, Gower drilling the ball into the heart of the box where Ashley Williams finished with a bullet header from close-range.
Leicester went searching for an immediate reply as they bombarded the Swansea City area with crosses and set-pieces, but de Vries and his defence were at hand to scupper their chances.
The Swans suffered a massive blow just before the half-hour as midfielder Joe Allen pulled up as he went in for a challenge; with the ball still in play he carried on for two minutes before eventually falling to the ground.
Following brief treatment on the field of play it was decided that he would no longer be able to take part and was replaced by Jordi Lopez, coming on to make his competitive debut in a Swans shirt.
Nathan Dyer was causing problems with his pace while Lopez was showing a number of classy touches in midfield.
The former Barcelona youngster had a hand in what was the Swans' best effort of the closing exchanges, picking out Shaun MacDonald who'd made an overlapping run down the right.
His pinpoint cross matched that of Gower's earlier corner and found the head of Gorka Pintado but his effort deflected off a Leicester player to drift wide of the target - but the referee awarded a goal kick instead of a corner, which wasn't favoured by the sizeable travelling crowd.
Matty Fryatt placed himself in a good position inside the area but as he went to pull the trigger, and as the fourth official raised his board to signify the addition of two extra minutes, Monk was on the scene to stick his foot in and block the strikers effort.
Half-Time: Leicester 0 Swans 1
The home side made two changes at the start of the second-half with King and Fryatt making way for Dany N'Guessan and new loan signing Martyn Waghorn.
The Swans kept with the same side that completed the first 45 minutes and within 90 seconds of the re-start Nathan Dyer won a corner, only for it to be cleared.
Foxes sub N'Guessan almost enjoyed the perfect start of his afternoon on 48 minutes as he struck the first shot on target of the second period, striking the ball with a half volley which looked goalbound only for Alan Tate to stand strong and block his effort.
The Leicester supporters started to wake up and had another N'Guessan effort to cheer 60 seconds later, which he fired across goal and wide, while Steve Howard saw another shot blocked to complete a constant spell of Leicester pressure.
But with 52 minutes played they were handed a lifeline when goal hero Ashley Williams brought down Bruno Berner inside the area following a sweeping move down the right.
The referee pointed to the spot, Steve Howard stepped up and placed the ball to Dorus' left but the Dutchman was quick to react and saved the penalty - his first in a competitive fixture for the Swans.
Paulo made his second change of the afternoon shortly after the hour when Andrea Orlandi came on in place of Shaun MacDonald and moments later the referee brandished his first yellow card of the game, shown to Richie Wellens following a challenge on Jordi Lopez.
Leicester were desperate to get themselves level and came close again on 67 minutes from a right-sided corner, the ball was kncocked back into the heart of the area and Howard struck a wicked volley which bounced back off a strong wall of Swansea City defenders.
Their equaliser did come moments later, Lloyd Dyer sending the unmarked Bruno Berner down the right, his cross was met by the first-time shot of debutant Waghorn who found the net with the aid of a wicked deflection.
And the Swans barely had time to regroup before suffering at the hands of another Foxes sub, Dany N'Guessan - the midfielder turning and shooting low into the corner of the net following a corner from the left-hand side.
Paulo's response was to put Stephen Dobbie on in attack, in place of Angel Rangel, as the formation shifted from 4-5-1 to 3-5-2.
It was almost game over six minutes from time as the visiting defence failed to pick up their man down the left, the cross came in from Nicky Adams to meet the head of the unmarked N'Guessan whose bullet header thundered back off the crossbar.
Stephen Dobbie fired a weak shot straight at Chris Weale while Adams again found space down the left before cutting in and seeing his effort deflect for a corner off the boot of Alan Tate.
Jordi Lopez fired inches wide of the post with a wicked half-volley deep into injury-time but the Swans were unable to get back on level terms on what was a disappointing afternoon for Paulo Sousa's charges in the Midlands.