Millwall have consistently been in the top six since early January, with strong form of 29 points from 14 games in that time.

That, allied with Boro’s wobble, had allowed the automatic spots to loom into view, and they showed that with a strong 1-1 draw at Ipswich last time out confirming their credentials.

But, having been second best throughout the first half, the visitors came out of their shells after the break and Brynn had saved superbly from Tristan Crama’s deflected effort before they did level.

Jake Cooper and Mihailo Ivanovic kept a corner alive and although Coburn’s volley was straight at the goalkeeper, it was so powerful that it squirmed over the line.

To their credit, they did not settle for a point and Azeez and Zak Sturge had chances to put them ahead.

But the last word went to Coburn, as he produced a moment of ruthlessness in front of goal that Boro had lacked.

The home side lost possession in their own half and when substitute Barry Bannan found him in the left corner of the area, the boyhood Boro supporter took aim and placed a lovely low curling finish beyond Brynn’s reach into the bottom corner.

Boro tried desperately to scramble a point in the five minutes of injury time, but Millwall held on as a return to the top flight for the first time in 36 years becomes a distinct possibility.