Just hours after top title contender Bayer Leverkusen lost 5-1 at Bayern Munich, Mario Gotze scored the opening goal for Dortmund in the 23rd minute and Robert Lewandowski made it 2-0 after 43 minutes.

Kevin Grosskreutz finished off Freiburg for good with his score in the 78th minute.

Dortmund extended their unbeaten streak to four games as they close in on their first league crown since the 2001-02 season.

Mario Gomez netted a first-half hat-trick as he guided Bayern Munich to a crushing 5-1 victory at home to Bayer Leverkusen in their first match since the sacking of coach Louis van Gaal.

Simon Rolfes scored an own goal to put Bayern on the board after seven minutes, before Gomez struck in the 28th and 44th minutes and one minute into first half stoppage time for a 4-0 half-time lead.

Eren Derdiyok pulled a goal back for Leverkusen after 62, minutes before Franck Ribery made it 5-1 with 15 minutes left.