MIDDLESBROUGH have one foot in the Championship play-offs after claiming a hugely-significant 2-1 win at promotion rivals Derby County.

Boro now have a four-point gap to Derby, who find themselves outside the top six, and will definitely qualify for the play-offs if they beat Millwall in their final home game of the campaign next weekend.

Their latest success came courtesy of one of their most accomplished displays of the season, with Mo Besic opening the scoring in the first half.

Britt Assombalonga added a second goal in the second period, and while David Nugent set up a nervy finale when he scored from the penalty spot in the 90th minute, Boro held on to claim a thoroughly-deserved success.

Tony Pulis was forced into once change from the side that beat Bristol City, with Assombalonga making his first start since February in place of Patrick Bamford, who was unavailable after suffering a head injury last weekend.

With both sides desperately needing a positive result to aid their attempts to claim a play-off place, it was no surprise that the game began at a frantic pace. Commendably, that tempo did not really drop for the following 90 minutes.

The tone was set in the very first minute, with Adam Clayton picking up a yellow card for a foul close to the halfway line, and Derby created the first opportunity shortly after, with Bradley Johnson heading Tom Lawrence’s corner wide of the target.

Boro’s first sight of goal came in the eighth minute, but while Daniel Ayala flicked George Friend’s long throw towards Assomablonga, the striker could only direct a weak header straight at Scott Carson.

Derby thought they should have had a penalty in the 19th minute, but while Friend appeared to lean into Matej Vydra as the Rams striker went down in the box, referee Lee Probert remained unmoved. It was a crucial decision, as just 60 seconds later, Boro were claiming the lead.

Adama Traore was a key figure all afternoon, with his driving runs and technical ability causing the Derby defence all kinds of problems.

Craig Forsyth thought he had tackled him as he broke down the right-hand side, but Traore picked himself up to deliver a cross into the centre. Besic took a touch before stepping inside the area, and while Carson got a hand to the midfielder’s shot, he was unable to prevent it finding the net.

Derby tried to rally through Nugent, but while the former Boro striker did well to get a shot away from distance, the ball drifted harmlessly wide of the post.

Lawrence found the target with a similar effort ten minutes before the break, but Boro goalkeeper Darren Randolph got down well to tip the ball around the upright.

There was no sign of the pace of the game relenting at the start of the second half, and Derby came close to claiming an equaliser when Nugent drilled a first-time effort into the side-netting after Andre Wisdom released him into the Boro box.

However, Boro continued to threaten themselves, especially from set-pieces. George Friend scored in last weekend’s win over Bristol City, and the full-back went close again as he nodded Traore’s corner over the crossbar after stealing in front of his marker at the front post.

The visitors also remained a threat from open play, and after Traore spearheaded a break from inside his own half, Jonny Howson cut in from the right-hand side to curl an excellent 22-yard effort against the crossbar. Moments later, Besic picked up a loose ball close to the edge of the area and fired a fierce drive over the bar.

With Derby desperately throwing men forward in search of an equaliser, Boro found themselves with space to exploit, but while Traore left two defenders for dead as he broke into the box, he was only able to drag a low effort wide of the target.

A second goal looked likely for much of the second period though, and it duly arrived with 20 minutes left.

It was an excellently-worked strike, with Howson releasing Traore down the right-hand side, and the winger firing a low cross to the feet on the unmarked Assombalonga. Boro’s leading scorer steadied himself on the edge of the six-yard box, before lashing past Carson’s right hand.

Curtis Davies volleyed wide from a corner as Derby tried to rally, and Randolph displayed some sharp reflexes as he clawed Lawrence’s goal-bound strike around the post.

Derby scored in the 90th minute as Nugent rolled home from the spot after Ayala was penalised for hauling down Davies at a corner, but Boro held on to claim all three points.

Derby (3-5-2): Carson; Keogh, Davies, Forsyth; Wisdom, Lawrence, Huddlestone (Hanson 71), Johnson, Olsson (Weimann 62); Vydra (Palmer 62), Nugent.

Subs (not used): Roos (gk), Pearce, Ledley, Jerome.

Middlesbrough (4-1-4-1): Randolph; Shotton, Ayala, Gibson, Friend; Clayton; Traore, Besic (Leadbitter 81), Howson, Downing (Fabio 85); Assombalonga.

Subs (not used): Konstantopoulos (gk), Cranie, Fry, Johnson, Harrison.