By James Pearson
Last Updated: 01/01/70 1:00am
The Bavarian side are Werder's nearest challengers, but goals from Ewerthon and defender Christian Worns sent Ottmar Hitzfeld's side to their fourth defeat of the campaign.
The visitors' misery was compounded after 68 minutes when influential midfielder Michael Ballack was sent off for collecting his second yellow card.
Stuttgart moved to within two points of Bayern after a 3-1 home success over lowly Eintracht Frankfurt.
Kevin Kuranyi's strike just before the break and Aleksander Hleb's second three minutes after the interval clinched the win.
Marcelo Bordon added a third with 11 minutes remaining to put the icing on the cake for Stuttgart, although Alexander Schur netted a consolation.
Hertha Berlin remain in relegation trouble after Ivo Ulich's late equaliser for Borussia Monchengladbach rescued a 1-1 draw after Roberto Pinto's early opener.
Wolfsburg secured their 11th win of the campaign after a convincing 4-0 success over 10-man Freiburg.
Maik Franz and Fernando Baiano already had the home side two-up before Roda Antar was dismissed.
Further efforts from Hans Sarpei and Diego Klimowicz put the icing on the cake.
1860 Munich are still looking over their shoulders following a 2-1 home reverse to Hamburg.
Paul Agostino netted late on, however it was not enough to nick a point after Nico-Jan Hoogma and Mehdi Mahdavikia put the visitors two-up.
Bayer Leverkusen remain in fourth following an impressive 3-2 victory over Schalke.
Dimitar Berbatov, Bernd Schneider and Hans-Jorg Butt scored for Bayer, the latter from the penalty spot, while Michael Delura and Mike Hankle netted for the home side.
Kaiserslautern edged out Hansa Rostock in a five-goal thriller at the Fritz-Walter Stadion.
Hansa were up against it when Gernot Plassnegger was sent off early doors and they were made to pay.
Nenad Bjelica and Marian Hristov scored for the Red Devils before Rene Rydlewicz pulled one back.
Rydlewicz's second from the penalty spot actually brought the scores level, but their was still time for Vratislav Lokvenc to snatch a winner.
Click below for match summaries:
1860 Munich 1-2 Hamburg
Borussia Dortmund 2-0 Bayern Munich
Borussia M'gladbach 1-1 Hertha Berlin
Kaiserslautern 3-2 Hansa Rostock
Schalke 2-3 Bayer Leverkusen
Stuttgart 3-1 Eintracht Frankfurt
Wolfsburg 4-0 Freiburg
Click here for the latest Bundesliga table.