Berlin (AFP) - Fresh from knocking Bayern Munich out of the German Cup, Freiburg will hope to again spoil the party against the same opponents on Saturday, this time at home.
Bayern lacked firepower in Freiburg's 2-1 win at the Allianz Arena on Tuesday, with their goal coming from centre-back Dayot Upamecano.
Star summer arrival Sadio Mane's drought in front of goal continues to frustrate the German champions.
Mane has played seven matches for Bayern since returning from a leg injury which forced him to miss Senegal's World Cup campaign, but has registered only one assist and no goals.
After Tuesday's match, a smiling Mane told reporters "soon, I promise you" after he was asked when he would return to the spectacular form he displayed with Liverpool.
Manager Thomas Tuchel, just two games into his Bayern reign, said he had "no doubt whatsoever about Sadio's quality and what he can bring us", explaining "it's only a matter of time."
Club chief executive Oliver Kahn said that Mane might be struggling because there is "a lot of competition" for starting spots at Bayern.
"He doesn't know that (from Liverpool) and is perhaps not used to it."
"He's still looking for himself."
Bayern lead with eight league matches to play but Borussia Dortmund, who face, Union Berlin are just two points behind.
Freiburg have lost just one league match at home this season and sit fourth, on track for what would be a first-ever Champions League qualification.
While barely cracking a smile, understated Freiburg manager Christian Streich said on Thursday he was "delighted as hell" ahead of Saturday's 'second leg' against the Bavarian behemoths.
"This is the maximum challenge, right after the maximum challenge" the 57-year-old manager said.
"It was a great event, but that was it.Now it's about what happens on Saturday."
The gruff manager promised his side "two days off, probably" after the match, an extra incentive for his exhausted charges to secure a second-successive upset.
One to watch: Jude Bellingham (Borussia Dortmund)
After their 4-2 thrashing at Bayern last weekend cost them top spot, Dortmund were eliminated from the German Cup with a 2-0 loss at RB Leipzig on Wednesday.
A loss on Saturday at home to Union Berlin in a second consecutive top-three clash, would allow the visitors to overtake Dortmund.That would reduce the chances of a title celebration on Dortmund's famous Borsigplatz come season's end.
To arrest the slide, Dortmund will need a return to form from midfielder Jude Bellingham.
The English teenager, who has clocked the most minutes of any Dortmund player this season, started on the bench in the Cup defeat.
When subbed on with 30 minutes remaining, Bellingham gestured to the visiting fans, telling them to turn up the noise.
Dortmund sporting director Sebastian Kehl praised Bellingham after the match for giving the side "a fresh wind", saying "he knows what the team needs".
On Saturday, Dortmund will need a refreshed Bellingham to beat Union and keep the pressure on leaders Bayern.
Key stats
0/6 - Freiburg have not beaten Bayern at home since being promoted to the top division in the 2016-17 season, losing four and drawing two.
5/5 - Dortmund have won all five of their home matches in all competitions against Union Berlin.
7 - Winning five and drawing two of their last seven, Mainz have emerged as dark horses for the European placings.
Fixtures (all times 1330 GMT unless otherwise stated)
Saturday
Borussia Dortmund v Union Berlin, Freiburg v Bayern Munich, Mainz v Werder Bremen, Augsburg v Cologne, Bayer Leverkusen v Eintracht Frankfurt, Hertha Berlin v RB Leipzig (1630 GMT)
Sunday
Borussia Moenchengladbach v Wolfsburg, Bochum v Stuttgart (1530 GMT), Hoffenheim v Schalke (1730 GMT)