Borussia Dortmund's awful run of results continued on Saturday when they were beaten 2-1 at home by Werder Bremen to heap further pressure on manager Peter Bosz.
Pierre-Emerick Aubamyang helped force an own goal to cancel out Maximilian Eggestein's first-half opener near the hour mark, but Theodor Gebre Selassie restored the visitors' lead on 65 minutes to consign Dortmund to a sixth defeat in their last nine matches in all competitions.
Dortmund, who previously led the league after a brilliant start, haven't won in the Bundesliga since September and defeat to relegation-threatened Bremen was the side's 10th game without a win in any competition.
Bremen made the better start with chances falling to Max Kruse and Zlatko Junuzovic before Eggestein struck in the 26th minute.
Kruse found the German under-21 midfielder on the edge of the penalty area, where Eggestein eluded a Dortmund defender and let fly inside the far post.
Dortmund were struggling to create an attacking threat with moves forward breaking down amid apparent uncertainty, much to home fans' frustration. They whistled their side off at the break, prompting Bosz to make two substitutions for the second half.
Shinji Kagawa drew a save from Jiri Pavlenka shortly after the break, signalling a change in attitude from the home side, who duly equalised before the hour mark with an own goal from Philipp Bargfrede under pressure from Aubameyang.
But Gebre Selassie put Bremen back in front minutes later when he was left free to convert a cross from Florian Kainz.
Dortmund, who previously led Bayern Munich by five points, are now 13 points behind the league leaders.
Dortmund have only won one of their 13 matches since the end of September -- a DFB-Pokal win at third-division Magdeburg -- and this latest defeat comes after they ended their Champions League group-stage campaign with just two points in midweek.
They remain on 22 points in the Bundesliga table, 13 behind leaders Bayern Munich, who won 1-0 at Eintracht Frankfurt on Saturday.