Millwall remain deep in relegation trouble as goals from Patrick Bamford (25mins), Kike (29mins) and Jelle Vossen (78mins) sent Middlesbrough to the top of the Championship table and left The Lions six points from safety.
It was very much a case of deja vu as The Lions looked quite comfortable in the opening exchanges, created and squandered a great chance to forge ahead and were then were made to pay for their profligacy as Boro scored twice in four minutes to take a commanding lead.
Following a cagey opening in which the two teams, both desperately looking for points to boost their challenges at the top and bottom of the table, effectively sized each other up, it was Millwall who carved out a great opportunity to break the deadlock.
Lee Gregory latched onto a ball over the top and with just keeper Dimi Konstantopoulos standing between him and goal glory, slightly hesitated and in doing so gave the Boro man a split-second to divert the striker's shot with his legs.
The home side responded and had three bites at the cherry as they in turn pressed for the opening goal. Kike headed straight at David Forde from a central position, Albert Adomah saw his effort blocked by Jimmy Abdou - making his 250th appearance for The Lions - and then Lee Tomlin was denied by Alan Dunne before Shaun Williams cleared the follow-up off the line.
The first goal was always going to be crucial and unfortunately it was Ian Holloway's side who conceded it on 25 minutes when the busy Tomlin combined with Adomah to set up Bamford, who finished calmly to hand the hosts a deserved lead.
Barely four minutes later Boro had doubled their advantage. Adam Clayton’s long ball found Bamford in the box and he in turn laid the ball off for Kike, who didn;t connect cleanly but still got enough purchase on the ball for it to bounce over the head of Forde and in.
Grant Leadbitter powered a header over the bar early in the second half following some neat wing play by former Barnet wideman Adomah Adomah, who also drew a smart save out of Forde with a stinging drive that the keeper did well to hold.
The Lions really struggled to get bodies forward to support Gregory and Gary Taylor-Fletcher, but did produce the move of the match shortly after midfielder Ed Upson had entered the fray. A slick five-man interchange sw the ball worked to the sub, who hit a crisp 20-yarder that flashed a whisker wide of the right upright.
However any faint hope of a barnstorming finish by Holloway's side were crushed almost instantly when Boro sub Vossen wrapped up the win with a simple finish from close range after Forde had denied George Friend.
Middlesbrough: Konstantopoulos, Friend, Fredericks, Gibson, Leadbitter (Forshaw, 82mins), Clayton, Kike, Tomlin (Vossen, 73mins), Bamford (Wildschut, 83mins), Kalas, Adomah. Subs not used: Ripley, Whitehead, Reach, Woodgate.
Bamford (25mins), Kike (29mins), Vossen (78mins)
Forde, Abdou, Dunne, Hooiveld, Harding, Tonge (O'Brien, 80mins), Williams (Upson, 65mins), Woolford, Fabbrini, Taylor-Fletcher, Gregory (Fuller, 65mins). Subs not used: King, Nelson, Beevers, Angel.
Ref: K Wright
Att: 16,078 (away 162)