Freiburg appeared to have gotten off the hook before half-time as defender Marc-Oliver Kempf looked to have handled the ball only for the incident not to be picked up.
After a delay of six minutes, Mainz were 1-0 up.
Defeat meant Freiburg dropped behind Mainz into the relegation zone due to an inferior goal-difference, with four games of the season remaining.
IPL 2018 Match 9 MI vs DD
Ishan Kishan only made nine runs, while Evin Lewis struck a 17-ball 29 before he was clean bowled by Siddarth Kaul. In his next over, Tewatia foxed Lewis by floating up a googly and drawing the mis-hit that was caught at mid off.
The players had already gone off for the interval when the German official Guido Winkmann consulted the video assistant referee (VAR) about a Freiburg handball in the last moments of the first-half.
Freiburg's players had to be summoned from the dressing room and back onto the pitch to allow the home side to take their penalty.
"It leaves a bitter taste", Freiburg sporting director Jochen Saier said.
VAR was introduced to eradicate refereeing mistakes and make the game smoother, so far it's only brought chaos though..
IPL 2018 Match 10 KKR vs SRH
KKR lost the last match against Chennai Super Kings by a whisker and captain Dinesh Karthik and his team didn't do much wrong. Hyderabad will be sweating while selecting the playing XI. "We have good power-hitters, and a good mix overall".
A Bundesliga match descended into chaos as the referee awarded a penalty during half-time after checking the VAR.
Indeed, the goal proved to be a major turning point and Mainz put the seal on a crucial victory in the 79th minute when De Blasis capitalised on a awful goalkeeping error to slot home.
Supporters also forced the game to be paused by throwing rolls of toilet paper on to the pitch as a protest against the Bundesliga's introduction of matches on Monday nights.
De Blasis, who'd had to wait for Alexander 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.
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She said that women and children have no religion and that no politics should be done over such issues. File images of Jammu and Kashmir ministers Chaudhary Lal Singh and Chander Prakash.