Sebastian Kehl has helped Dortmund to carve out three points against Freiburg while Mainz denied Berlin a victory in the German Bundesliga.
Dortmund defeated Freiburg for the eighth consecutive time as Kehl's winner ensured the 15th win of the season for the "BVB", reports Xinhua.
The victory tightens Dortmund's second place, having a four-point advantage to third placed Leverkusen. Freiburg recorded their 13th loss in 24 games to remain second from the bottom with just 19 points.
Dortmund broke the deadlock just before the hour mark when team captain Kehl scored the only goal of the match from 27 meters with a well-placed curl over Freiburg custodian Oliver Baumann.
"It was a difficult game for us. We scored our goal, although a lucky one. I can live with that 1-0 victory," Dortmund coach Juergen Klopp said.
Mainz snatched one point on home soil against Berlin following a 1-1 draw.
Berlin scored through Adrian Ramos, his 15th goal of the season, in the 51st minute.
Berlin blew the chance of getting three points when Sami Allagui brought down Joo-Ho Park inside the box to concede a penalty and Eric-Maxim Choupo-Moting beat Berlin's goalkeeper Thomas Kraft to the bottom left corner at the 65th minute.
Mainz slip from 6th to 7th position with 38 points while Berlin slump from 8th to 9th place with 36 points.