Pierre-Emerick Aubameyang scored the winner as Borussia Dortmund boosted their Champions League qualification hopes with a 1-0 home Bundesliga victory over RB Leipzig.
Leipzig came into the match knowing a victory would move them to within one point of leaders Bayern Munich after the champions' surprise draw with Schalke earlier on Saturday, but instead the gap has increased to four over the weekend.
Dortmund move up to third in the table, above Hoffenheim on goal difference and within eight points of Ralph Hasenhuttl's side above them.
Leipzig were greeted by negative banners attacking their ownership at Signal Iduna Park and their day did not get better when Aubameyang ended a two-match league spell without a goal by netting with a first-half header to move onto 17 league goals this season.
Thomas Tuchel had called for focus from his forward ahead of the game after he had publicly discussed transfer speculation and got the response he was looking for as the Gabon international's strike proved decisive.
Leipzig's away form is becoming a huge concern to their hopes of keeping pace with Bayern - they have lost three straight top-flight matches on the road - although they can count themselves unlucky that substitute Federico Palacios-Martinez's injury-time strike was ruled out after he strayed marginally offside.
Leipzig were without key players Timo Werner, Emil Forsberg and Marcel Sabitzer, but still threatened first when Willi Orban sent a header straight at Roman Burki after being found by Rani Khedira, one of the visitors' three changes.
Dortmund responded when Ousmane Dembele - in as one of Tuchel's three alterations - showed superb pace down the right and crossed for Aubameyang, who headed over.
That duo combined again in the 35th minute and this time there was no mistake with the finish, Dembele cruising past defenders Marvin Compper and Orban before his cross took out goalkeeper Peter Gulacsi to leave Aubameyang with a simple task to head in from inside the six-yard box.
Dortmund wasted a glorious chance to double their lead early in the second half when Aubameyang led a rapid counterattack and fed Reus, but the Germany international scuffed a left-footed finish wide with only Gulacsi to beat.
Another opportunity went begging when Aubameyang raced clear after Reus had turned creator, the league's top scorer working half a yard of space away from Compper before sending a poor finish straight at Gulacsi.
Dortmund suffered a major blow when the impressive Dembele pulled up with an injury on the hour mark, Christian Pulisic replacing him.
The hosts' profligacy continued when Reus fired another excellent chance wide after Lukasz Piszczek produced a clever throughball on his 250th club appearance.
Reus then failed to beat Gulacsi with yet another opportunity from close range before Leipzig's Dayotchanculle Upamecano somehow cleared substitute Matthias Ginter's effort off the line.
Leipzig failed to force Burki into a single second-half save, but almost grabbed a stoppage-time leveller when Palacios-Martinez found the bottom corner, only for the assistant to correctly flag for offside as Dortmund held out for a deserved victory that extended their unbeaten home league run to 30 games.