Fullkrug’s first-half strike and Brandt’s effort 11 minutes from time secured a 2-0 Group F victory in front of a sell-out 81,365 crowd at Signal Iduna Park to go with their 1-0 success at St James’ Park two weeks ago.
But the outcome might have been very different had Joelinton not headed wide from point-blank range at 1-0 amid a concerted fightback by the Premier League side, who have now taken four points from as many games, three fewer than Dortmund.
Edin Terzic’s men will nevertheless feel they were good value for their win on a night when they bounced back from a nightmare 4-0 defeat by arch rivals Bayern Munich on their own pitch in determined fashion, to the delight of their famous Yellow Wall.
For Magpies head coach Eddie Howe, whose side must realistically take at least a point at Paris St Germain later this month to stand any chance of progressing, it proved a sobering evening as he was forced to abandon his initial plan to field 19-year-old Lewis Hall at left-back at half-time after an early booking left him in severe jeopardy.
Hall had stepped into a team left threadbare by injuries in which Tino Livramento started on the right side of a three-man frontline.
Hall left himself on a tightrope when he was booked for hauling back Fullkrug after Brandt had played a pass in behind him, and he was relieved to see his sliced effort to clear Brandt’s resulting free-kick loop over his own crossbar.
Nick Pope was called upon for the first time to parry Fullkrug’s 13th-minute strike after slick inter-play between Felix Nmecha and Brandt, and he had to be just as resilient three minutes later to repel Karim Adeyemi’s attempt with the home side building momentum.
Newcastle edged their way into the game and forced an opening when Kieran Trippier and Hall worked a short corner move, only for the teenager’s driven cross to elude all his waiting team-mates.
The visitors’ task grew in difficulty with 26 minutes gone when, having passed up several opportunities to clear their lines, they were punished when Fullkrug stabbed Marcel Sabitzer’s scuffed cross past Pope from close range.
Dortmund keeper Gregor Kobel dealt comfortably with Fabian Schar’s goal-bound header from a Trippier corner, while the hosts nearly increased their lead nine minutes before the break when Sabitzer lifted a shot wastefully over at the end of a pacy attack.
The Magpies had a chance to level on the stroke of half-time when Jamaal Lascelles returned Trippier’s corner across goal, but Joelinton’s header was picked off by Kobel to cap a difficult half for the visitors.
His side instantly looked better balanced and Kobel had to turn away a dangerous Livramento cross before Almiron scooped a shot wide of his right post, although Pope had to palm away a Brandt snapshot as the hosts responded.
However, Newcastle should have been back in it 11 minutes after the break when Bruno Guimaraes played Livramento into space down the right and his cross was perfectly weighted to present Joelinton with a free header, which he planted wide with the goal at his mercy.
An increasingly open game left both defences exposed, but it was Newcastle’s which was picked apart with 11 minutes remaining after Trippier’s free-kick had failed to beat the first man.
Adeyemi sent the ball upfield to leave Livramento to deal with both Brandt and Sabitzer, and the former kept his cool to draw the defender and fire low past Pope.