The Italian Referees' Association (AIA) has apologised to AC Milan for a mistake during their shock defeat to Spezia on Monday evening.
With the Serie A game level at 1-1, referee Marco Serra failed to play advantage after Milan ace Ante Rebic was fouled just outside the box.
That denied the hosts a scoring opportunity, as Junior Messias whipped the ball into the top corner while Serra mistakenly blew his whistle.
Serra looked distraught after the incident, apologetically holding his hands up to the complaining Milan players surrounding him.
The referee's error proved costly, as Emmanuel Gyasi went on to score a 96th-minute winner for struggling Spezia at the San Siro.
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According to La Gazzetta dello Sport via Football Italia, Serra now faces a "lengthy" suspension for his mistake.
AIA are thought to have noticed several errors from the official during the game and may suspended him for longer than two games.
Serra apologised to Milan at full-time and, as reported by Italian outlet Milan News, was in tears over the incident.
It's believed four or five Milan players - including Zlatan Ibrahimovic - consoled the devastated official, showing a touch of class in a difficult moment.
The result leaves the Rossoneri second in Serie A, two points behind rivals and champions Inter Milan having played a game more.
Milan's next three games could define their season. They face Juventus and Inter in the league and have a Coppa Italia quarter-final against either Lazio or Udinese.
Milan are already out of Europe after finishing bottom of their Champions League group.
"Losing a match like this must give us great strength to react," said Milan manager Stefano Pioli after the controversial result.
"We pay dearly for our mistakes in both phases, but then there are other responsibilities as well. It's a real shame... we lost composure after the decisive episode of the match.
"There was a desire to win the match, but that episode sent us into confusion. We made a mistake on the second goal, it is evident, we all lost our attention."
On the referee, Pioli added: "He made a mistake, he noticed immediately and he also apologised. Unfortunately, it went like this.
"He made a serious mistake, he even admitted it. Unfortunately it is a bad evening, everything went wrong. However, he needs the energy to react immediately."
Spezia manager Thiago Motta, who won the Champions League twice as a player with Barcelona and Inter, insisted: "The lads deserve the praise.
"We knew it was a difficult game against a team that is in the race to win the title. We did well until the end.
"We know that Milan are really strong, they have quality players, they are attacking-minded but can leave some space at the back and we made the most of it.
"We could have scored other goals in the second half and, overall, I believe we deserved to win."