AIDEN O'Brien scored a brilliant hat-trick to fire Millwall to their second league win of the season.
O'Brien was making his first league start this campaign – and rewarded his manager Neil Harris in spectacular fashion as Crewe were dispatched 3-1 at Gresty Road.
The 21-year-old striker put the away side ahead on 21 minutes with a smart left-foot finish in the box after some neat work in the build-up by Carlos Edwards.
But Crewe levelled when Bradden Inman's shot came off Lauri Dalla Valle to wrong-foot Jordan Archer 15 minutes later.
Crewe should have gone ahead on 56 minutes but Archer produced two brilliant point-blank saves to deny first Harry Davis and then Dalla Valle.
O'Brien got his second when he latched onto a loose ball 25 yards out and turned to arrow a rasping drive past Ben Garratt.
And he competed his hat-trick when he made space for himself in the box to drive home a left-footed effort low inside Garratt's near post in the 74th minute.
O'Brien was rewarded for his good recent form with a place up front alongside Steve Morison. Ed Upson and Shaun Williams replaced Ben Thompson and Jack Powell from the 2-0 defeat to Chesterfield as Harris set his side up in a 4-4-2 formation, with Upson wide on the left.
It didn't take too long for that move to look inspired when Edwards, starting at right-back in place of the injured Shaun Cummings, initiated a move by playing a one-two with O'Brien before setting up Morison for a shot. Garratt got in the way but O'Brien followed up to twist his body and turn the ball into the net with his left foot.
That was the first goal scored by a Millwall striker in the league since the opening-day defeat of Shrewsbury and it got even better when O'Brien lashed in to restore Millwall's lead.
He said during the week if he got a chance he'd take it – and he certainly walked the walk at the ground where Harris broke the Lions' goal-scoring record.
And he completed the first hat-trick by a Millwall player since Lee Gregory scored three against Derby last season with a superb finish to give the Lions three vital points.
A clash of principles and styles
Crewe have a philosophical blueprint that was laid down by Dario Gradi and they are sticking to it.
Perhaps that ethos explains why, even at 1-0 down in the first half despite having had more possession, the Gresty Road crowd never sounded like it was going to get on the players' backs. In fact, every positive move and every corner won was cheered enthusiastically.
Up until their equaliser they had moved the ball from side to side but hadn't really looked like carving Millwall's defence open. Given their approach, though, they arguably deserved the chunk of luck they got when the ball came off Dalla Valle and rolled past Archer to make it 1-1 10 minutes before the break.
Millwall were more direct, and they possibly should have gone in ahead at the break only for Morison to meekly shoot at Garratt when he had the space and time to take the ball further towards goal.
Crewe stuck at it, but O'Brien was the big difference between the sides.
Millwall could have a goal-scoring gem in O'Brien. This was the first hat-trick of his senior Lions career, of course, and all his five Millwall goals have come away from home.
It was a treble of such high quality. The first showed 21-year-old's instinct for shadowing play and being in the right place to finish with his left foot. He drove in the second from distance, but the pick of the haul was the third. Four red shirts converged on him when he received the ball but he tricked past them with some beautifully nimble footwork before he sent two more players the wrong way and dispatched the shot with his left boot as a seventh opponent tried and failed to stop him.
O'Brien was born in north London but his family are Irish and he has already played for Ireland under-21s. On this evidence it will be a big surprise if he doesn't go on to win a senior cap.
So early in the season, but it still feels like such a crucial week with games against sides around them in the League One table. It hardly bears thinking about what a defeat here would have done to morale. And it so easily could have happened had Crewe taken those chances early in the second half.
This is a huge boost for Millwall. And it's a huge boost that it was a striker who helped clinch the points after the Lions had gone four games without a centre-forward getting on the scoresheet.
Archer also continues to look an astute acquisition as he showcased his rapid reflexes.
And there was a first league start this season for right-back Edwards, who even though he approaches his 37th birthday showed his experience could be crucial this season.
"I thought we were fantastic. First and foremost I need to talk about Aiden – what a hat-trick. He's got the ability and quality to do that. It wasn't just his goals, his all-round performance was good.
"The back four were much better, much more aware of danger.
"I thought all over the park, I thought the subs that came on played their part, I thought we managed the game really well and that's the pleasing thing."
Crewe: 4-4-2: 1 Garratt; 2 Turton, 4 Davis, 6 Nugent, 17 Kingsley; 15 Fox (H Wilson, 67), 8 Atkinson, 16 King, 10 Inman; 12 Dalla Valle (Cooper, 80), 27 Colclough.
Substitutes: 3 Guthrie, 5 Ray, 9 Haber, 11 Cooper, 13 Richards, 19 Baillie, 24 H Wilson,
Millwall: 4-4-2: 13 Archer; 4 Edwards, 15 Nelson (Webster, 51), 16 Beevers, 5 Craig; 10 Onyedinma (Ferguson, 69), 6 Williams, 26 Abdou, 8 Upson; 20 Morison, 22 O'Brien (Gregory, 84).
Substitutes: 1 Forde, 7 Cowan-Hall, 9 Gregory, 14 Marquis, 17 Webster, 18 Ferguson, 24 Thompson.
Referee: Darren Handley
As it happened
Image: Millwall FC