On a snowy afternoon, defender Mats Hummels opened the scoring in the 23rd minute when he dived to head home a 40-metre cross from Turkish midfielder Nuri Sahin.

Robert Lewandowski, who replaced injured Paraguayan striker Lucas Barrios in Dortmund's starting line-up, wrapped up the win two minutes from time.

He gathered a loose ball inside the area, turned and hit a left-foot shot into the bottom corner of the net.

Egyptian striker Zidan, who has just recovered from a serious knee injury he picked up last April, was kept on the bench throughout the game.

He made his long-awaited comeback after a seven-month layoff on Thursday when Dortmund defeated Karpaty Lviv of Ukraine 3-0 in the Europa League.

Dortmund look firm favorites to win the Bundesliga title for the first time since 2002.

They made sure they would enter the winter break on the top of the table as they lead second-placed and surprise package Mainz with 10 points.