Millwall substitute Tom Bradshaw's 69th-minute leveller against Luton proved the first of three goals in 12 minutes for Gary Rowett's rampant Lions

Championship promotion hopefuls Millwall came from a goal down at half-time to batter hapless Luton Town in the second half at The Den.

Sonny Bradley's unmarked header earned the relegation-threatened Hatters a deserved interval lead.

But a tactical switch by home boss Gary Rowett paid dividends after the break as Millwall eventually capitalised on their almost total second-half dominance to score three times and condemn Luton to a fifth loss in six games.

Substitute Tom Bradshaw nodded in strike partner Matt Smith's far-post header to equalise on 69 minutes.

Then fellow sub Connor Mahoney cut in from the left to curl home a right-foot beauty on 78 minutes before crossing from the left just three minutes later for Smith to power home a classic centre-forward's header.

Rowett's Millwall are now sixth, even after the conclusion of the rest of the New Year's Day fixtures.

Graeme Jones' Luton are now bottom of the second tier following Wigan Athletic's 3-2 win over Birmingham City at St Andrew's.

Luton looked more than capable of avoiding their ninth successive away defeat when they had the better of a faltering first 45 minutes of football in the EFL in 2020.

Pelly-Ruddock Mpanzu, from 25 yards, and James Bree's curling right-foot volley both brought saves from Bartosz Bialkowski. And the home keeper was then an unsighted spectator when Alan Sheehan's free-kick picked out defender Bradley, who steered home his header from 12 yards.

Sonny Bradley had not scored since scoring Luton's very first goal of the season, the opening night 3-3 home draw with Middlesbrough

But Rowett's change of formation and the 42nd-minute introduction of Bradshaw to give better support up front to target man Smith made it a totally different story after the break.

Jed Wallace twice tested Luton keeper James Shea, who got down to his right to parry an awkwardly bouncing right-foot 30-yard shot and then again when Smith knocked down for Wallace to test him again with a right-foot volley from closer range.

Smith's header then clipped the top of the bar, Bradley got away with a blatant shirt tug in the penalty area on Jake Cooper and, in trying to beat team-mate Smith and touch in a deflected cross at the far post, the stretching Cooper unwittingly cleared a goalbound effort off the Luton line.

But a goal was coming - and the floodgates finally broke when, from Wallace's right-wing cross, Smith rose at the far post and picked out Bradshaw, who nodded in from close range.

Mahoney the doubled the lead just seven minutes after coming on when he made a jinking run to the edge of the Luton penalty area, and shimmied to his right before curling home.

And the points were wrapped up when Mahoney cross from the left for Smith - almost unplayable after the break - to beat the hesitant Shea to a textbook far-post header.

Millwall manager Gary Rowett:

"I just felt Connor might give us a moment of magic because he's got that quality. "It was a fabulous run from him. He fakes to shoot, the defender slides in and it just opens the space up momentarily.

"Then we could put the foot on the gas, another fabulous ball in from Connor and Smith doesn't miss from there. It's why he's in the team.

"I said to them at half-time, 'you're a goal down, you've performed poorly, I don't really care about the result, I just want to see a better performance. Be braver.

"We started the second half with a much better intensity, pinned them in and put them under pressure. And when you're in the position Luton are in, if we could get the first goal in the second half, we knew we'd go on and win."

Luton Town manager Graeme Jones:

"The game plan worked really, really well, but we couldn't sustain it. It's been the story of our away season, since Blackburn. I could talk about the positives, but I don't think anyone wants to hear that. It was a resolute display, for 70 minutes. But we couldn't hold out.

"The linesman's flag goes at 1-0 up, but the referee plays advantage and the wrong thing from our players is not playing to the whistle. I had five players stopping - the ball goes in the box, goal.

"On the second goal I've got (centre-back) Matty Pearson dribbling up the pitch - I've certainly never asked him to do that - and in transition Alan Sheehan is running back and he gets cramp.

"And that is just the definition of where we are at the minute. We need to have a level head, be sensible, get our best players fit, and we need to get some reinforcements in."