Camilo Zuniga's own goal proved too little too late for the Yellow-Blacks, who finished the match with ten men following Roman Weidenfeller's red card, as goals from Gonzalo Higuain and Lorenzo Insigne secured the Italian table-toppers three hard-fought points.
Dortmund suffer setback
Following on from their impressive 6-2 victory against Hamburger SV on Saturday, Dortmund set the tone in the early stages, putting their opponents under pressure from the off. However, it was the hosts who carved out the first sight of goal, as Insigne sent out an initial warning to BVB by curled an effort just wide approaching the quarter-hour mark.
Clear-cut chances began presenting themselves with more regularity at either end in the high-paced encounter, with Dortmund not only enjoying a larger share of possession, but also looking the more threatening side. Nuri Sahin, Robert Lewandowski and Marco Reus all failed to get the better of Pepe Reina.
Woes of Weidenfeller
The visitors were punished for their profligacy though, when Higuain ghosted in front of Marcel Schmelzer to head past Weidenfeller. Things proceeded to go from bad to worse, as Mats Hummels was forced off injured before Dortmund's No1 received his marching orders for handling the ball outside the box on the cusp of half-time.
A man down, Dortmund adopted a more cautious approach early in the second half, as the match settled down following an explosive start. Aside from Gökhan Inler's long-range drive, which stung the palms of Weidenfeller replacement Mitch Langerack, and Reus firing over from Pierre-Emerick Aubameyang's drilled cross, neither side created much.
BVB had been resilient in defence, but with an hour played Napoli began turning the screw, leaving ten-men Dortmund little time to breathe at the back. However, it wasn't from open play that they extended their lead, instead SSC doubled their advantage Insigne bent a delicious free-kick around the wall and into the top corner, leaving Langerak with no chance in goal.
Despite falling further behind there was no sign of a white flag being flown in the Borussia camp, as Aubameyang's dipping effort cannoned back off the bar, while Nuri Sahin's long-range effort failed to get the better of Reina. The Bundesliga leaders were rewarded for their efforts late on when Zuniga back-heeled Reus' cross into his own goal and, though Reus' late free-kick had Napoli's Spanish keeper at full stretch, the goal proved to be nothing more than a consolation effort at the end of a difficult night for Dortmund.
Napoli: Reina - Maggio, Cannavaro, Albiol, Zuniga - Behrami, Inler - Callejon, Hamsik, Insigne (73' Mertens) - Higuain (78' Pandev)
Dortmund: Weidenfeller - Großkreutz, Subotic, Hummels (45' Aubameyang), Schmelzer - Bender, Sahin - Blaszczykowski (45' Langerak), Mkhitaryan (76' Hofmann), Reus - Lewandowski
Goals: 1-0 Higuain (29'), 2-0 Insigne (67'), 2-1 Zuniga O.G. (87')