BERLIN (Reuters) - Borussia Dortmund, Bundesliga runners-up for the last two seasons and champions the two seasons before that, went back to the bottom of the table after a scrappy goalless draw at Bayer Leverkusen on Saturday.
VfB Stuttgart also dropped into the relegation zone after losing 1-0 at home to Borussia Moenchengladbach and goal shy Hamburg SV were hovering perilously close after losing 2-0 at home to Cologne.
Nils Petersen scored a second-half hat-trick to lift SC Freiburg off the bottom with a 4-1 win over Eintracht Frankfurt despite going behind in the first minute.
The Black Forest team climbed to 13th in the 18-team table with 18 points from 18 games, ahead of Hertha Berlin on goal difference. Hamburg, Werder Bremen and Stuttgart all have 17 and Dortmund 16
Dortmund, who have won only four league games and are enduring their worst season since 1984/85, battled hard but both sides struggled to create openings.
"We are in a relegation battle and there is no room for Champagne football," said Borussia coach Juergen Klopp. "I'm completely satisfied with the performance today, it's a small step and we need some stability."
The real action was elsewhere, notably in Freiburg where Marco Russ put Frankfurt ahead after only 41 seconds and the visitors barely broke sweat as they strolled through the first hour.
The game changed completely when Vladimir Darida converted a 61st minute penalty, before Petersen sprang into action as he turned in Felix Klaus's cross three minutes later and then headed home a Mike Frantz cross five minutes after that.
Petersen rounded off Freiburg's third win of the season when he scored at the second attempt in the 88th minute after his first header was blocked on the line.
Marco Hoeger's first-half goal gave fourth-placed Schalke 04 a 1-0 win over Hanover 96, although they had Dutch striker Klaas-Jan Huntelaar sent off for a ugly tackle from behind in the 85th minute.
Yunus Malli scored twice to set Mainz 05 on the way to a 5-0 win over Paderborn, before Pablo de Blasis, Sami Allagui and Johannes Geis, from a penalty, shared the other goals in the mid-table clash.
Hamburg SV, the league's lowest scorers with only nine goals, drew another blank in a 2-0 home defeat to Cologne after Marcel Risse scored twice in the second half.
VfB Stuttgart, who like Hamburg have 17 points, were beaten 1-0 at home by Borussia Moenchengladbach who went third with 30 points ahead of Schalke on goal difference.