Darius Henderson bagged his first hat-trick for Millwall as Kenny Jackett's Lions clicked into gear in devastating fashion with a convincing win to stun big-spending Leicester City.
Henderson became the first Millwall player to score three since Jason Puncheon's treble against Crystal Palace on 1st January 2011, and the first to hit a treble away from The Den since Neil Harris' treble at Stockport in October 2009!
Despite struggling to score goals this season, a paltry return of three in the last 10 starts, The Lions displays in 1-1 draws against Middlesbrough and Brighton hinted that the corner was being turned.
But few amongst the 501 band of travelling fans could have dreamed that Millwall would demolish promotion-chasing Leicester quite so comfortably as Henderson banged home goals after 35, 45 and 67 minutes.
It was fitting that skipper Paul Robinson marked his 300th appearance for The Lions with a clean sheet and three points because he led by example to help Jackett's men record their biggest win against The Foxes in 70 years.
The Lions were excellent value for this victory too, bagging two goals in the opening half to put themselves firmly in the driving seat.
Leicester chalked up seven corners in the first 45 minutes, but found Millwall impossible to penetrate, as the visitors defended magnificently.
A brilliant 15th-minute block by Robinson to deny Jermaine Beckford as he shaped to shoot set the standard of a gutsy, disciplined and determined display by Jackett's charges.
Robbo was again the man averting the danger on 22 minutes when Beckford fell cheaply under pressure from the lionhearted defender as he tried to connect with Paul Konchesky's left-wing cross, but despite his half-hearted penalty appeals for a penalty, referee Eddie Ilderton was having none of it and rightly awarded a corner instead.
Having thwarted Leicester every which way they turned, it was The Lions who created the first decent scoring opportunity just before the half-hour mark. Brian Howard won possession from Yuki Abe, threaded the ball to Henderson who did well to work space on the left before squaring for the onrushing Simpson, only to have the ball nicked off his toes by keeper Kasper Schmeichel.
Abe drilled a low shot a couple of yards wide soon after for Leicester but it was Millwall who took the lead 10 minutes before the break.
Sol Bamba was penalised for a foul on Howard as he broke into the danger zone, referee Ilderton pointed to the spot and Henderson did the business with a fierce penalty that flew into the top left corner beyond Schmeichel's reach.
Further great defensive blocks by Robinson and Darren Ward - who felt the full force of Konchesky's piledriver - protected The Lions' lead as the game moved deep into first-half injury-time.
With Leicester pushing on in search of an equaliser, a quick incisive counter-attack by Millwall paid off handsomely. Henderson picked out Simpson in space, he returned the favour with a precision pass back to Henderson who had ghosted in at the far post and the former Watford striker produced a low angled drive that gave Schmeichel no chance.
Leicester introduced Darius Vassell and former Lions loanee Lloyd Dyer at the start of the second half and it was no surprise that The Foxes flew out of the traps in a buid to get a foothold back ito the game.
But Millwall dealt superbly with wave after wave of attack, and when Lee Peltier's shot did beat keeper David Forde on 53 minutes, the woodwork came to the rescue to deny the right-back.
Dyer fired into the side netting after Forde did well to narrow the angle and then Michael Johnson's 20-yarder flew narrowly over as The Foxes tried without success to find a way through.
Jackett's men responded in perfect fashion and put the game beyond Leicester's reach courtesy of Henderson's third and decisive goal. There were 23 minutes remaining when Liam Feeney swung over the third of Millwall's three corners in the match and Henderson stole in to head home after the home defence had failed to clear the danger.
That third goal banished any remaining fears that The Foxes would somehow claw their way back, and in fact it could have been worse for the home side with both Simpson and Howard having efforts blocked, whilst former Leicester striker Dany N'Guessan drilled a shot over the bar late on.
Andy King sent a header narrowly wide of the target, but by then a Leicester goal would have been merely a cosmetic alteration to the scoreline and Millwall comfortably played out four minutes of injury-time to clinch three points to move out of the bottom three.
Leicester City: Schmeichel, Peltier, Konchesky, Bamba, King, St Ledger, Johnson (Fernandes, 74mins), Wellens, Beckford (Vassell, 46mins), Abe (Dyer, 46mins), Nugent. Subs not used: Pantsil, Weale.
Bookings: Bamba (35mins), Johnson (37mins), Nugent (77mins)
Millwall: Forde, Dunne, Smith, Abdou, Robinson, Ward, Howard, Trotter, Henderson, Simpson (N'Guessan, 77mins), Feeney (Henry, 75mins). Subs not used:Mildenhall, Mkandawire, Agyemang.
Booking: Robinson (74mins)
Scorer: Henderson (35mins, pen, 45+3mins, 67mins)
Ref: E. Ilderton
Att: 21,991 (away 501)