Jurgen Klopp's men were not made to work hard for a place in the DFB-Pokal third round, as they ran riot at the Scholz Arena, with the 20-year-old on song
Mats Hummels got the ball rolling, and Marcel Schmelzer made it two just before the break. Mario Gotze grabbed a third with a sublime chip, and Julian Schieber rounded off the victory with his first goal for the club. Micahel Klauss then pulled one back for the hosts, but it was too little too late.
The visitors dominated proceedings from start to finish, and came close to taking the lead as early as the fourth minute. Kevin Grosskreutz collected Ivan Perisic's cross brilliantly, but his curling effort sailed far past the post when he should have done better.
Soon after, a Gotze corner was cleared as far as Neven Subotic on the edge of the box, but Jasmin Fezjic managed to get down well and block the Serbia international's effort.
It seemed like a matter of time before the champions broke the deadlock, and they were inches from doing so on 17 minutes when Robert Lewandowski turned on the edge of the box and unleashed a fantastic shot which cannoned off th cross bar, with Fezjic completely beaten.
Then, however, the Aalen resistance was broken. Gotze scooped the ball into the box and found Grosskreutz, who fed Hummels, and the Germany international finished from a narrow angle.
After going a goal up, Dortmund controlled possession, and soon enough, it was two. Lewandowski fed Leitner, who in turn fed Schmelzer, and the Germany left-back finished with ease.
BVB were in complete control. All Aalen had to show for their efforts was a 14th-minute from Klauss which Roman Weidenfeller did well to beat away.
The second half started in much the same vein. Gotze collected Lewandowski's pass on the edge of the box, dribbled through two defenders, and chipped it over Fejzic to make it three.
Jurgen Klopp's side were now clear, and there was a feeling that they could pick their number for the night. Perisic was sent clear, but Fejzic was quick off his line to smother the danger, before the Croatian sent an effort just over the bar from 20 yards.
The fourth finally arrived 12 minutes from time. Lewandowski had an effort blocked from close range, but Schieber was there to tap it into the empty net via the post.
Klauss pulled one back late on with an excellent free kick which swung over Weidenfeller and into the net, but it mattered little. Dortmund had done more than enough to secure a place in the next round.