MIDDLESBROUGH are guaranteed a place in the Championship play-offs after goals from Britt Assombalonga and Jonny Howson secured a 2-0 win over Millwall.

Boro have booked their play-off place with a game to spare, although the identity of their opponents will not be clear until they have completed their campaign at Ipswich Town next Sunday.

They could face Cardiff City, Fulham or Aston Villa, but will fancy their chances against any of the trio if they can repeat this afternoon’s impressively accomplished performance.

They were the dominant force throughout as they effectively ended Millwall’s own hopes of making the play-offs, with Assombalonga opening the scoring as he raced on to a long ball in the 12th minute.

Their victory was sealed midway through the second half, with Jordan Archer’s goalkeeping error enabling Jonny Howson to tap home from close range.

Tony Pulis stuck with the side that won at Derby last weekend, which meant Adam Clayton and Assombalonga retained a place in the starting line-up ahead of Grant Leadbitter and Patrick Bamford, who were confined to the bench.

Assombalonga scored in the win at Pride Park, and Boro’s leading scorer was at it again as he opened the scoring with his side’s first threatening attack of the game in the 12th minute.

It was a wonderful solo effort, with Assombalonga controlling Daniel Ayala’s long ball out of defence, turning inside Millwall full-back Mahlon Romeo and firing home a low effort that found the back of the net via the inside of the post.

Assombalonga has spent much of his time under Tony Pulis on the substitutes’ bench, but the record signing now boasts 15 league goals for the season, an impressive tally given his recent lack of involvement.

The goal was Boro’s reward for a bright, industrious opening, and the hosts went on to dominate the majority of the first half, albeit without being able to carve out a large number of chances.

Millwall’s well-organised 4-4-2 formation made it difficult for the Teessiders to make much of an impression in the final third, and while Mo Besic made some dangerous breaks from midfield, Adama Traore had one of his quieter games as he constantly found himself surrounded by opposition defenders.

Stewart Downing shanked a shot well wide shortly before the half-hour mark, and the former England winger came closer to adding a second goal moments later as he cut in from the left-hand side to fire in a low effort that deflected wide off Ryan Tunnicliffe.

Downing swung the resulting corner into the penalty area, enabling an off-balance Ayala to head wide at the back post.

Downing saw another shot blocked by an excellent sliding challenge from Shaun Hutchinson on the stroke of half-time, and while Steve Morison headed Shaun Williams’ corner over the bar in first-half stoppage time, the interval arrived without Boro goalkeeper Darren Randolph having been forced into a save.

Boro’s dominance continued at the start of the second half, with Traore passing up an excellent chance to double his side’s lead.

Besic’s floated through ball played the winger behind the Millwall defence, but he sliced his shot well wide of the target.

Assombalonga was twice denied by some excellent last-ditch tackling as Boro continued to press in search of a second goal, but Ayala was forced to mop up to deny Lee Gregory as Millwall made a rare foray into the Boro area midway through the second half.

Boro needed a second goal to give them a degree of comfort, and when it arrived in the 66th minute, it owed much to a glaring error from Archer.

The Millwall goalkeeper allowed Downing’s left-wing cross to slip through his grasp, leaving Howson with the simple task of slotting home from inside the six-yard box.

Millwall’s best chance of getting back into the game came with nine minutes left, but while Gregory aimed an angled header at goal, Randolph was able to make a routine save.

Middlesbrough (4-1-4-1): Randolph, Shotton, Ayala, Gibson, Friend, Clayton, Traore, Besic, Howson, Downing (Fabio 81), Assombalonga (Bamford 77). Subs (not used): Konstantopoulos (gk), Cranie, Fry, Leadbitter, Harrison.

Millwall (4-4-2): Archer, Romeo (McLaughlin 38), Hutchinson, Cooper, Meredith (Ferguson 83), Wallace, Williams, Tunnicliffe, Marshall (Elliott 54); Gregory, Morison. Subs (not used): Martin (gk), Thompson, Onyedinma, O’Brien