Swedish teenager Alexander Isak shone for holders Borussia Dortmund on Tuesday in their 5-0 German Cup second-round romp at third-division Magdeburg.

The 18-year-old Isak scored and set up a goal on his first start for the club with star striker Pierre-Emerick Aubayemang rested by the Cup holders.

Isak signed in January from Stockholm club AIK for a reported nine million euros ($10.5m).

Dortmund hope the Sweden international, who had previously only made four substitute appearances for the side, can grow to become Aubameyang's future replacement.

Isak laid on a goal for Gonzalo Castro, who scored with his first touch of the ball on 42 minutes, then showed ice-cool finishing by slotting home on 47 minutes.

The floodgates opened in the final 16 minutes as Ukraine winger Andriy Yarmolenko converted a penalty after a handball as Magdeburg's defence tired.

Defender Marc Bartra netted a header before Shinji Kagawa added a fifth on 90 minutes.

This was Dortmund's first win in four games having seen their five-point lead evaporate in the Bundesliga, but they stay top of the league on goal difference from Bayern Munich.

Dortmund coach Peter Bosz made seven changes from the side which 2-2 drew at Eintracht Frankfurt last Saturday.

Captain Marcel Schmelzer made his first start after six weeks out with a leg injury, while Germany winger Andre Schuerrle came on for Isak late on to make his comeback after injury in August.

Schalke are also into the third round after their 3-1 win at third-division Wehen WI, while Eintracht Frankfurt enjoyed a 4-0 thrashing of fourth-tier Schweinfurt.

The plum tie of the round takes place on Wednesday when RB Leipzig host Bayern Munich in a clash of last season's Bundesliga top two.