Winkmann then blew for half-time, prompting both sets of players to make their way to their respective dressing rooms, but he dramatically called them back after speaking with the VAR and penalized Freiburg for handball.
A 2-0 victory in a relegation six-pointer in the German Bundesliga was marred by video assistant referee (VAR) controversy when a penalty was awarded at half-time - when the sprinklers were already on and the players had gone down the tunnel.
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.
Mainz midfielder Pablo de Blasis scored the penalty to put the hosts 1-0 up.
La Liga, however, has opted to bring in VAR for 2018-19, while lawmakers have given the green light for video replays to be used at the 2018 World Cup in Russian Federation.
De Blasis sealed the win late on to earn Mainz their first win in seven games.
South Africa's anti-apartheid icon Winnie Mandela laid to rest
It will be Ramaphosa's first visit to the area following the Marikana massacre that saw over 40 people being killed by the police. Ramaphosa asked South Africans to honour the stalwart by uniting. "She kept the memories of our father alive.
The confusion continued after the break, as fans threw toilet rolls onto the pitch in protest against Monday night games, delaying the restart by several minutes.
Mainz climbed to 15th on goal difference above Freiburg who fell to 16th, the relegation playoff spot.
Afterwards, Freiburg sporting director Jochen Saier said: 'It leaves a bitter taste'. I can't understand why referees are involved in the decision-making process at all, if it is to be used for clear and obvious errors, surely the VAR has to tell the referee what the decision is.
The Premier League agreed last week to delay the introduction of the...
So moments after blowing the half-time whistle the referee opted to consult the VAR system.