Darius Henderson hit his second hat-trick in successive games as Millwall marched to their first away win since 22nd October with a vital victory at Barnsley.
Henderson, who marked his return from injury with a treble against Dagenham & Redbridge on Tuesday night, was on hand to fire home the opener from the penalty spot on 36 minutes, add a second three minutes later before taking his season's tally to 15 with a clincial third goal 15 minutes from time.
Saturday's win at Oakwell was as welcome as it was overdue for Kenny Jackett's men, who grabbed this game by the scruff of the neck from the opening minute and imposed themselves, adapting far better to the difficult windy conditions.
"It's been a good response by the players following the Birmingham result, which was a bit of a freak result because we actually played very well in that game," said boss Kenny Jackett.
"Since then we've had a 5-0 win against Dagenham and are still in the FA Cup and now a 3-1 victory at a very tough place.
Darius Henderson has been vital for us, and you could see that from the quality of his finishing.
We really have something to build on and the confidence gained from today means we can kick on positively over the next three months."
Skipper Paul Robinson was ruled out with a slight thigh injury paving the way for Tony Craig to partner Darren Ward in the heart of the Millwall defence.
It was the only change made to a Lions side determined to build on Tuesday night's thumping 5-0 FA Cup win over Dagenham & Redbridge.
Pitched against a Barnsley outfit sitting comfortably in the middle of the Championship table, this was always going to be a tougher test than John Still's League Two Daggers.
In theory anyway that should have been the case, but from the opening minute it was obvious that Barnsley's jittery defensive backline were going to be in for an uncomfortable afternoon.
It was easy to see why Keith Hill's Tykes had failed to keep a clean sheet in their nine previous outings, and difficult to understand that this was a Millwall side which had bagged just seven league goals on their travels away from The Den this season.
Jackett's men started confidently and certainly enjoyed large chunks of possession with Liam Feeney's crisp second-minute drive held by Luke Steele in the home goal.
Harry Kane then sent a header over the bar from a deep Hamer Bouazza corner before the left winger's stinging long-range effort flew high over the bar from around 25 yards after Henderson had flicked the ball into his path.
A misunderstanding between Forde and right back Jack Smith caused an anxious moment on 18 minutes, but the ball ricocheted clear for a corner which Millwall dealt with comfortably.
Millwall kept plugging away and finally made the breakthrough nine minutes before the break when Miles Addison, who had been spoken to moments earlier for a slightly rash challenge, hauled Trotter to the floor as he rose to get on the end of a Bouazza free-kick. The assistant referee was in a great position and immediately brought the infringement to referee James Adcock's attention.
Top scorer Henderson grabbed the ball, laced up his boots and then promptly despatched a precision finish from the penalty spot that gave Steele no chance.
Henderson added his - and Millwall's - second of the game barely three minutes later, controlling a super diagonal pass from Jimmy Abdou before stroking the ball past Steele once more.
Barnsley came out at the start of the second-half looking to get an early foothold back in the game, but it was Millwall who threatened again, this time Bouazza's fierce free-kick stinging the palms of Steele in the home goal.
Ricardo Vaz Te's shot forced Forde to bravely grab the ball through a sea of bodies on 53 minutes with Millwall responding immediately, the tireless Kane's powerful run and cross down the left flank setting up Liam Feeney, the latter's shot flying over the bar.
Barnsley appealed for a penalty just before the hour mark when Darren Ward and Chris Dagnall collided in the danger zone, but with the home players still questioning the officials, Millwall broke with pace and power and so nearly added a third goal. Stand-in skipper Trotter picked up the ball on the edge of his own area, powered forward before slipping the ball to Bouazza. Trotter continued bombing forward and picked up Bouazza's return pass before despatching a low shot that flew narrowly wide.
Kane, clearly relishing playing alongside Henderson, beat the offside trap as he ran onto Feeney's through ball, only to be denied by an excellent low save by Steele.
However the Lions didn't have to wait much longer for their third goal of the game, and how fitting that it was hitman Henderson who provided the finish, smashing home an unstoppable effort into the bottom left hand corner from 16 yards.
Although Barnsley hauled a goal back a couple of minutes from time when McNulty converted from close range after Vaz Te had capitalised on some defensive over-play by Smith, The Lions had already done enough to ensure three points were heading back down to south London.Barnsley: Steele, Hassell (Wiseman, 63mins), McNulty, Foster, McEveley, Dagnall (Done, 63mins), Perkins, Addison, Vaz Te, Gray, Davies (Taylor, 53mins). Subs not used: Preece, Edwards.
Bookings: Addison (34mins), Davies (75mins)
Scorer: McNulty (88mins)
Millwall: Forde, Smith, Barron, Abdou, Craig, Ward, Bouazza (Henry, 66mins), Trotter, Henderson, Kane, Feeney. Subs not used: Mildenhall, Wright, N'Guessan, Marquis.
Booking: Henderson (76mins)
Scorer: Henderson (34mins, pen, 39, 75mins)
Ref: J Adcock