Striker Florian Niederlechner netted both of Freiburg's goals in their shock 2-1 comeback win at Bundesliga high-fliers Eintracht Frankfurt on Sunday to leave them just outside the top six.
Eintracht crashed to only their second defeat at home this season despite taking an early lead when Sweden striker Branimir Hrgota converted their first chance on 11 minutes.
Freiburg, last season's second division champions, forced their way back into the game as Niederlechner rounded Frankfurt goalkeeper Lukas Hradecky on 25 minutes to score.
Sixth-placed Frankfurt had the ball in the Freiburg net moments later when Ante Rebic headed home, but the referee disallowed the goal as midfielder Mijat Gacinovic had fouled goalkeeper Alexander Schwolow.
Niederlechner netted again on 59 minutes for the winner when he finished off a flowing move, although replays showed he was offside.
"For the goal, he was at least a metre offside. If I hadn't seen it, I'd have had to ask myself why not?" fumed Frankfurt coach Niko Kovac, who had a heated discussion with the referee at the final whistle.
"You could go further and say we should have had two penalties."
Frankfurt's burly captain Alexander Meier, the league's top scorer in 2014/15, came off the bench in the last 10 minutes and nearly rescued a point, but his close-range shot was saved by Schwolow.
The result lifted Freiburg to eighth -- two points from the top six European qualification places -- and 23 points behind league leaders Bayern Munich, who are seven clear of the chasing pack after Saturday's 3-0 win at Cologne.
Frankfurt's next league game on Saturday is in Munich. They held Carlo Ancelotti's Bayern to a 2-2 draw when the teams last met in October.
Later, relegation-threatened Hamburg extended their unbeaten home run in the league to seven matches with a 1-0 win over Hertha Berlin, thanks to a late winner from Swedish midfielder Albin Ekdal.
Hamburg's win leaves them 16th -- still in the relegation places -- but means the teams below them, Ingolstadt and Darmstadt, are now at least five points from safety.
Hertha's dreadful form on the road continued with a sixth straight away defeat in all competitions, yet Pal Dardai's team are fifth.
"Of course I am disappointed," said Dardai.
"The first-half had little to do with football and we conceded a goal out of the blue.
"Hamburg were a tick more aggressive than us and the defeat certainly hurts."