"It's very curious," Freiburg goalkeeper Alexander Schwolow said of the VAR decision made after referee Guido Winkmann had blown the halftime whistle.
Winkmann, who allowed play to continue after Daniel Brosinski's shot took a deflection off Freiburg defender Marc Oliver Kempf's hand, was on his way off the pitch when notified by video referee Bibiana Steinhaus, who was watching in Cologne, that he should check a replay.
Winkmann watched the incident again on the pitch-side screen and evidently decided Kempf deliberately put his hand to the ball.
But Freiburg's players were already off the pitch and entering their changing room when they had to be called back.
"We're not going out," Freiburg coach Christian Streich responded as he led his confused players back into the changing room. Some were looking at TVs to determine exactly what was going on.
Freiburg eventually emerged back onto the pitch, where Winkmann explained to a bemused Streich that it was for a penalty for the home side.
De Blasis, who'd had to wait for Schwolow to re-take his place in goal, held his nerve to score inside the left corner as the Freiburg 'keeper dived the other way.
"We thought that when the whistle goes for halftime, that the first 45 minutes are ticked off," Freiburg sporting director Jochen Saier told Eurosport at halftime. "That wasn't the case in this scene, we have to accept that with heavy hearts. Things are getting stranger."
After finally getting their halftime break, the players were forced to wait again for the second half after Mainz fans threw hundreds of rolls of toilet paper onto the pitch in protest against Monday night games. After the stewards cleared the paper strands, they threw another round they held back in reserve to delay the second half even further.
Protests also delayed the initial kickoff, and the whole game took place to the sound of shrill whistles as supporters made their displeasure known with the German football league.
A mistake from Schwolow in the final minutes allowed De Blasis to seal his side's first home win since January.
Defeat meant Freiburg took Mainz's place in the relegation zone due to an inferior goal difference. Wolfsburg is also under threat with four rounds remaining, while survival looks increasingly unlikely for Hamburger SV and Cologne, eight and nine points adrift of safety, respectively.
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