Harry Smith crowned a superb week by marking his debut in the Football League with the fourth and final goal as Millwall swept aside 10-man Bristol Rovers to record the biggest win of the season for Neil Harris' Lions.
Smith, who scored two goals on his senior debut in the midweek Checkatrade Trophy game at Luton, followed up in style as The Lions took full advantage of their numerical advantage with goals from Aiden O'Brien (22mins), Shaun Williams (64mins), Lee Gregory (68mins) and Smith (88mins).
Millwall had the first opportunity of the game within the opening two minutes when a neat interchange between Smith and Gregory saw the latter hit a shot with the outside of the boot, only to see his effort fly a foot over.
Ben Thompson acrobatically hooked off the line at full stretch after 10 minutes to keep out Ellis Harrison's downward header and deny Rovers as the game really opened up.
At the other end Gregory showed great control before threading a pass to Thompson on the edge of the penalty area; he in turn held off a strong challenge before firing a stinging shot over the bar.
Matty Taylor was a whisker away with a thumping drive moments later, but then in Millwall's next attack in the 14th-minute, O'Brien was bundled over by Daniel Leadbitter on the edge of the penalty area and the right-back was shown a straight red card from referee Andrew Madley.
The Lions were energised by their numerical advantage - as were the home fans - and Harris' men really began to turn the screw.
Smith was denied a certain goal by the agility of Kelle Roos who somehow got a hand to keep out the debutant's goalbound header.
Both Shaun Williams and Joe Martin had free-kicks cleared, but The Lions were not to be denied and when Gregory's snap-shot was parried by Roos, there was O'Brien to slot home the opening goal with 22 minutes on the clock.
Despite enjoying the majority of possesion, Harris' men had to be content with a solitary one-goal lead going into half-time as Rovers shut up shop for the remainder of the opening 45 minutes.
Smith was denied again within four second-half minutes, reacting to a loose ball and hitting a low skimmer that Roos could only parry, but Gregory was adjudged to have fouled as he raced to try and connect with the follow-up.
A powerful run by Hiram Boateng so nearly conjured an unlikely equaliser just before the hour mark, but having burst through the home defence the midfielder's low angled drive was blocked by Archer at the near post for a corner.
It took a great interception by Tony Craig, and then another piece of cool defending by the skipper, to avert the danger as Rovers enjoyed their best spell of pressure.
The Lions, however, stood firm and could have doubled their tally on 61 minutes when Gregory's firm cross was met by Williams, but his diving header flashed narrowly wide of the upright.
Williams made no mistake at the second time of asking, when Gregory nudged the ball into his path from sub David Worrall's 64th-minute cross, the midfielder rifled an angled drive that flew into the back of the net.
Gregory was rewarded for an excellent afternoon's work with a goal just four minutes later. Joe Martin provided the cross, Smith rose majestically to flick into Gregory's path and the frontman did what he does best - lashing the ball home with aplomb.
Smith by now had engaged in a personal battle to beat keepe Roos, the stopper this time clawing away the front man's firm header as Millwall pressed once more.
It looked as though he was running out of time to cap an impressive first showing at The Den, but with just two minutes remaining some sloppy defending by the disheartened Rovers rearguard handed Smith time and space to pick his spot, calmly slotting home from a central position with the final goal of a memorable afternoon.
Archer, Martin, Craig, Williams (Cummings, 86mins), Thompson (Thompson, 72mins), Gregory, Onyedinma, Romeo, Webster, O'Brien (Worrall, 62mins), Smith. Subs not used: King, Wylde, Pavey, Rooney.
Booking: Onyedinma (86mins)
Scorers: O'Brien (22mins), Williams (64mins), Gregory (68mins), Smith (88mins)Bristol Rovers:
Roos, Leadbitter, Brown, Lockyer, Hartley, Harrison, Taylor (Easter, 73mins), Lines, Sinclair, Boateng (Montano, 65mins), Colkett (McChrystal, 23mins). Subs not used: Puddy, Clarke, Gaffney, James.
: 9,645 (away 1,018)