BRENDAN RODGERS must have feared his Foxes had reached the end of the road on their latest European adventure.
But Leicester dramatically changed direction to triumph in the Daka rally.
Summer signing Patson Daka struck a sensational nine-minute hat-trick either side of half-time to wipe out Spartak's two-goal lead - then set the seal on a fantastic individual display with a late fourth to make this a night the Zambian will never forget.
Leicester did their best to undo all their good work when they conceded a late goal to Aleksandr Sobolev, who scored his second of the night to set up a nervy finale.
Normally that would have made the Russian a match-winning hero - but he could only manage 50 per cent of Daka's amazing tally!
Suddenly Leicester are back in business in Group C as their £23million summer signing from RB Salzburg paid back a hefty chunk of that investment.
Instead of ending the night rock bottom of their group, the Foxes surged into second place ahead of the clash between group rivals Napoli and surprise leaders Legia Warsaw.
And Rodgers will be confident his battlers can seize control of the group with back-to-back wins against Spartak and Legia before their final group game in Naples.
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Yet early on, Leicester's latest Europa League campaign looked in danger of becoming a real Sob story when they were mugged after 11 minutes in Moscow.
A flukey deflected goal from Spartak's 6ft 5in striker Aleksandr Sobolev appeared to set the tone for another miserable night abroad when his attempted cross struck Ricardo Pereira's backside to leave Kasper Schmeichel hopelessly wrong-footed.
Worse followed just before half-time when Jordan Larsson - son of former Celtic, Barcelona and Manchester United striker Henrik - cashed in on some woeful defending by Caglar Soyuncu to drill home a low Victor Moses cross.
At that point Leicester must have known what Manchester United felt like at the weekend when they hustled them out of their stride.
But it appears Rodgers' side are made of sterner stuff than Ole Gunnar Solskjaer's strutting superstars.
They rolled up their sleeves to snatch a crucial lifeline within a minute of Spartak's second goal, to head in at half-time with renewed hope.
Kelechi Iheanacho's through ball landed at Daka's feet and the 23-year-old striker sprinted clear before beating Aleksandr Maksimento, who got a glove to the ball but couldn't prevent it finding his net.
It made Rodgers' half-time talk a whole lot more positive and the Foxes cashed in on their feelgood factor with a rapid equaliser within three minutes of the restart.
Luke Thomas sent Iheanacho clear and when the Nigerian striker centred Daka hared in to knock the ball into the unguarded net.
Incredibly, six minutes later Leicester were in the lead as Daka completed an extraordinary hat-trick which took a mere nine minutes in match time.
Youri Tielemans threaded a perfect pass to the striker and super-confident Daka calmly nut-megged Maksimento to put Leicester 3-2 up.
Amazingly, there was more to come from the Zambian who then capped an astonishing performance by becoming Leicester's all-time leading scorer in Europe after starting the evening on zero goals.
With 11 minutes remaining James Maddison turned provider with a sublime through ball and Daka easily beat Spartak's demoralised goalie - before flipping and somersaulting his way into the record books as he celebrated his extraordinary feat.
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Having turned the tie on it's head, Daka was then made to go through the wringer as Spartak snatched a late lifeline.
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Once again former Chelsea man Victor Moses turned provider for Sobolev to fire home from close range.
But there was only ever going to be one winner by then as Daka rightly took the plaudits on the final whistle.