The in-form Japanese forward gave Dortmund a deserved lead four minutes after the restart.

Polish midfielder Lukasz Piszczek powered down the right flank and pulled the ball back for the onrushing Kagawa to rifle a shot home from the edge of the area.

The lively 21-year-old orchestrated wave after wave of attacks as a ruthless Dortmund side kept the visitors' defenders on their toes throughout the game.

Paraguayan striker Lucas Barrios wrapped up the victory in the 70th minute after rounding off a flowing move.

Kevin Grosskreutz connected with a low cross at the far post to back-heel the ball for Barrios, who tapped in into an empty net.

There was no room for Egyptian striker Mohamed Zidan, who was expected to feature in the game after recovering from a serious knee injury he picked up last April.

The 28-year-old is likely to face a stern challenge to regain his place in Dortmund's starting line-up, given the impressive displays of the likes of Kagawa and Mario Gotze.

Dortmund have 31 points from 12 games, seven ahead of second-placed Mainz who face Hanover 96 on Saturday.