Joel Piroe's double helped Leeds United to a 3-0 victory at Millwall as the Whites registered their second win of the Championship season.
The Dutch striker rounded off a slick counter-attack to open the scoring in the 15th minute, finishing low across Lions keeper Bartosz Bialkowski and into the bottom right-hand corner.
The hosts claimed a foul on Kevin Nisbet in the build-up before Georginio Rutter swept upfield and exchanged passes with Wilfried Gnonto before feeding Piroe in the box.
Leeds had their second with 13 minutes left when Piroe tapped in from close range after Dan James stumbled in attempting to convert Rutter's cut-back, with the latter finishing emphatically from 15 yards to wrap it up late on.
With influential midfielder Zian Flemming dropped to the bench, Millwall offered little in reply - although Ryan Longman and Tom Bradshaw tested visiting goalkeeper Illan Meslier either side of half-time when the score was 1-0.
Leeds move up to 10th in the Championship, two points off the play-offs, after winning at The Den for the first time since March 2012 while Millwall are 18th following a third defeat in five league outings.
Whites oozing class in attack
Piroe netted 41 league goals over the course of his two-year spell at Swansea and has settled in quickly since his move to Elland Road last month for a fee reported to be more than £10m.
Having held on to Gnonto and Crysencio Summerville during the summer transfer window - and with Rutter playing with confidence - Leeds look to have the threat up front to mount a promotion challenge as boss Daniel Farke seeks an immediate return to the Premier League.
Millwall dominated the opening period in front of a raucous home crowd, with Jake Cooper and Allan Campbell having efforts blocked, but fell behind to a swift and perfectly executed move from the visitors.
The Lions first claimed a penalty for handball against Luke Ayling - who was lying prone in the area but controlled the ball with his head - and then a foul on Nisbet by Piroe, but Archie Gray fed Rutter and the Frenchman progressed into the Millwall half before finding Gnonto on the left hand side.
Gnonto returned the ball to Rutter, who slipped in Piroe and the striker controlled with the outside of his right boot before sliding his low finish past Bialkowski.
Leeds came close to a second when Summerville clipped an effort across goal from a narrow angle on the right hand side of the box, and soon after Longman called Meslier into a diving save with a curling shot from just inside the area.
Bradshaw sent a snapshot straight at the Leeds keeper right after the restart, but the second half saw few clear-cut openings until Leeds netted twice in the space of five minutes to make it a miserable afternoon for Gary Rowett's Millwall.
Millwall manager Gary Rowett told BBC Radio London:
"I don't ever like to soft-soap a 3-0 defeat or say 'That's okay' because we don't want to be like that as a team and a club against Leeds, where there is a real healthy rivalry between the fanbases,
"As opposed to the Norwich game, where I didn't think we were aggressive enough or competed like we need to compete, I thought we made it difficult for Leeds.
"We had lots of good moments and good pressure but couldn't quite turn that into good chances or goals.
"At 1-0 I had a decision as a manager - do I stick or do I twist? We are at home and wanted to try and go for it and that left us a bit open on the counter and we got done two more times."
Leeds United boss Daniel Farke told BBC Radio Leeds:
"To win three points on such a tough ground in this manner in a tight game and return with a clean sheet, it is good for confidence and our rhythm.
"I am pretty pleased with our goals. The first was an unbelievable team goal.
"But you also need to do the dirty work. If you are willing to work hard and act as one unit, then our quality can shine and it is also quite enjoyable.
"We spoke about the atmosphere and about the soft skills that we need. All the compliments go to my lads because they delivered exactly what I was asking for.
"England is the motherland of football and more or less my second home. To be allowed to work for such an unbelievable, emotional and amazing club like Leeds United is good fun.
"There is a lot of responsibility and pressure as well, but I enjoy it."