Borussia Dortmund beat Bayer Leverkusen 1-0 in a controversial encounter at the BayArena on Sunday that saw the hosts' coach Roger Schmidt initially refuse to leave the touchline after being sent off.
In a tight contest between second-placed Dortmund and Leverkusen in fourth, Pierre-Emerick Aubameyang's second-half winner proved the difference, although Schmidt's antics and the subsequent suspension of play proved the major talking point.
Schmidt felt there was a foul in the build-up to Aubameyang's goal and, despite being sent to the stands by referee Felix Zwayer, the Leverkusen boss refused to leave the touchline.
Zwayer opted to suspend proceedings as players and officials left the field, with striker Stefan Kiessling sent to discuss the matter with his coach.
After play got back under way, Leverkusen failed to claim a point against Thomas Tuchel's side, who move back to within eight points of leaders Bayern Munich.
Schalke had the chance to go above Leverkusen into fourth but were denied maximum points by Martin Harnik's late equaliser in their 1-1 draw with Stuttgart at the Veltins Arena.
Younes Belhanda's second goal for the club 14 minutes in looked to have been enough for the hosts, only for Harnik to level 16 minutes from time as Stuttgart's five-match winning run in the league was halted.
At the bottom, Hannover's top-flight future was made even more uncertain by a 1-0 home defeat to fellow strugglers Augsburg.
Second-bottom Hoffenheim were 3-2 winners over Mainz on Saturday and Koo Ja-cheol's early winner at the HDI-Arena moved Augsburg four points off the bottom three.
Thomas Schaaf's Hannover are four points adrift at the bottom, having lost their last eight Bundesliga games while scoring just once since early December.
