The result puts Freiburg, last season's second division champions, back up into sixth place, which carries a Europa League berth next season, with four games left.

Christian Streich's youthful team claimed another big scalp after recent wins over Cologne, Eintracht Frankfurt and Wolfsburg.

Ex-Bayern Munich striker Nils Petersen gave hosts Freiburg the lead at their Schwarzwald Stadion before Germany forward Kevin Volland converted a second-penalty for Leverkusen.

But the hosts picked up the three points when winger Pascal Stenzel, on loan from Borussia Dortmund, came off the bench to finish a counter-attack.

The 21-year-old hit the winner when he drilled the ball past Leverkusen's Germany goalkeeper Bernd Leno two minutes from time after a brilliant run down the left wing.

It was another disappointing result for Leverkusen, who reached the Champions League last 16 this season, but have won just one of their last ten games and are 12th -- only four points from the bottom three.

On Saturday, Thiago Alcantara's second-half equaliser rescued Bayern Munich in their 2-2 draw at home to Mainz as the runaway leaders twice came from behind.

Having bowed out of the Champions League quarter-finals at Real Madrid in midweek, the draw caps a week to forget for Bayern, who are winless in their last four games.

Mainz twice took the lead in Munich as ex-Barcelona midfielder Bojan Krkic netted an early goal and Daniel Brosinski's converted a second-half penalty, but strikes by Arjen Robben and Thiago gave Bayern a point.

Second-placed RB Leipzig can cut Bayern's lead to six points by winning at Schalke on Sunday evening.

It was a poor performance from double-chasing Bayern ahead of Wednesday's German Cup semi-final at home to Borussia Dortmund.

Pierre-Emerick Aubameyang, the league's top-scorer, hit his 27th league goal this season as Raphael Guerreiro headed the winner in Borussia Dortmund's 3-2 win at Borussia Moenchengladbach to climb to third.

Gabon hot-shot Aubameyang crept one goal ahead of Bayern's Robert Lewandowski in the race to be the league's top-scorer this season.

Pascal Stenzel

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