Swedish teenager Alexander Isak -- dubbed the 'Mini Zlatan' -- has taken a step out of the shadow of Pierre-Emerick Aubameyang at Borussia Dortmund with his man-of-the-match performance in the German Cup.

The lanky 18-year-old set up the first goal, then netted his own with ice-cool finishing in a 5-0 romp at third-division Madgeburg in the second round of the cup on Tuesday on his first start for the holders.

In his home country, Isak is regarded as the next big Swedish star to follow in the footsteps of national hero Zlatan Ibrahimovic and German daily Bild coined the 'Mini Zlatan' nickname.

However, in Dortmund he plays second-fiddle to Gabon hot-shot Aubameyang, the Bundesliga's top scorer last season.

As Aubameyang sat out the cup win with a leg knock, his understudy seized his chance on only his fifth senior appearance for the German club.

"He has enormous potential, but first of all he had to come out of his shell," admitted Dortmund coach Peter Bosz after his side booked their place in the third round.

Isak was just 17 when he joined Dortmund for 8.6 million euros ($10.1m) in January from Swedish club AIK after interest from Real Madrid.

He made his first start for Borussia after nine months at the club and three appearances this season off the bench.

However, team-mate Nuri Sahin said Isak must beef up physically to cope with the demands of the Bundesliga.

"When you have an ox like Sokratis (defender Sokratis Papastathopoulos) in front of you and challenging for the ball, it's going to hurt. He had to learn that," Sahin said of Isak.

"'Auba' had (injury) problems, so you need to bring a boy like that (Isak) along. We paid a lot of money for him.

"He played well, but as a newcomer he has to get stronger still."

Isak cut a shy figure in the mixed zone after his man-of-the-match display at Magdeburg.

"It was a good game from me, I got the chance and I took it," said the teenager.

However, he was quick to shake off Ibrahimovic comparisons, insisting "No, I'm not Zlatan -- I'm Alex."

He is part of a crop of talented teenagers at Dortmund.

England Under-17 international Jadon Sancho, who only turns 18 in March, made his Bundesliga debut in last Saturday's 2-2 draw at Eintracht Frankfurt.

And 19-year-old senior USA international Christian Pulisic already has a regular place in the starting team.

However, Isak's only chance of keeping his place for Saturday's league match at Hanover 96 for the leaders is if Aubameyang, who has so far scored ten goals in nine league games, fails to recover from a leg knock.

"(Isak) is working hard, even in training, but it's not easy for him with Aubameyang in front of him," admitted Bosz.