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Michael Carrick’s Reds, who beat Premier League Chelsea in Wednesday's (AEDT) Carabao Cup semi-final first leg, claimed another London scalp.

Joe Bryan opened the scoring for the home side at The Den but goals from Lukas Engel, Isaiah Jones and Marcus Forss turned things around in favour of the Teessiders.

Millwall took a deserved 10th-minute lead, as the visitors cracked under early pressure.

Ryan Longman’s cross was cleared but only into the path of Bryan, who guided his effort into the bottom right corner from outside the box.

The Lions came close to doubling their lead five minutes later. Bryan turned creator and whipped a dangerous cross into the six-yard box, with centre-back Jake Cooper’s first-time effort clipping the bar.

Boro spent large parts of the first half on the back foot but managed to break forward and equalise seven minutes before the interval.

Jones, whose positive form carried on after his impressive display against Chelsea, threaded a pass to Sam Greenwood. The on-loan Leeds United player found Engel with a low cross and the unmarked Dane levelled with a close-range finish.

The visitors took the lead in the 58th minute after Bryan misjudged heading a high ball, with pacey former Tooting and Mitcham player Jones advancing and coolly finishing past Matija Sarkic.

Millwall sought a way back into the game but failed to replicate its dominance of the early stages and played slow passes around the back, much to the frustration of animated manager Joe Edwards.

The visitors turned the screw and looked the most likely to score again.

Substitute Matt Crooks showed quick feet, turning his man in midfield before unleashing debutant Luke Ayling down the right. The former Leeds right-back produced an excellent pass for Morgan Rogers, who failed to connect properly.

However, the points were sealed in added time when Forss scored as the visitors moved into the top half of the table.