Former referee Mark Halsey has claimed Liverpool fans sent him death threats after he sent off one of their players in a Premier League meeting with Manchester United.
Halsey took charge of more than 250 games across more than a decade as a Premier League ref, handing out 27 red cards at a rate of close to one every 10 games.
However, one of those reds in particular - shown to Jonjo Shelvey when the England international was on the Reds' books - led to a situation which he has described as "the worst it's ever got".
Now, the long-retired official has shed more light on the reaction he received from fans of the Anfield club, as well as Liverpool's own response to the events.
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Liverpool had endured a tough start to the season when they hosted Man Utd in September 2012, with none of Brendan Rodgers' first four league games in charge resulting in victory.
Their task became harder when Shelvey was shown a straight red card before half-time, and the visitors emerged victorious at Anfield thanks to goals from Rafael and Robin van Persie despite Steven Gerrard putting Liverpool in front.
Rodgers' team would subsequently go eight league games without defeat, but the response to Shelvey's dismissal is something the referee remembers vividly.
"The worst it's ever got was back when I was refereeing, in particular it was a Liverpool v Man United game in 2012," said Halsey, speaking exclusively to Ladbrokes at the launch of its 5-A-Side bet on Chelsea v Liverpool.
"I sent Jonjo Shelvey off in the first-half after he went in for a challenge with Jonny Evans. Liverpool went on to lose the match 2-1, and afterwards I received death threats towards me and my family, from Liverpool supporters.
"The police had to step in and thankfully they sorted it for me, and the club - to their credit - were fantastic in how they dealt with things.
"I got a lovely letter from Liverpool Football Club after it had all happened, condemning what their fans had done, which I really appreciated."
Liverpool's then-manager Rodgers criticised the red card decision himself at the time, suggesting United defender Evans could also have been dismissed.
"Of what we could control I thought the players and performance level was outstanding, what we couldn't control were decisions by the referee," he said.
"If Shelvey gets sent off for having both feet off the ground then Evans has to get sent off for that as well if you watch the replays.
"Jonjo is coming in from the side, it is a tackle the player has to go for and one the United player has to go for but the Liverpool player can't get sent off and the United one stay on the field."
Halsey, who has also spoken of a couple of "really bad" incidents on social media, also explained why he opted against taking time off after the Liverpool game in question.
"I remember, that game was on a Sunday afternoon, and then I was supposed to be refereeing a Southampton game on either the Tuesday or the Wednesday in the League Cup," he said.
"I was asked if I wanted to be removed from that game, but I said no, because then they win, don't they? So I went down there to referee the game, and had no problems.
"The PGMOL management were there at that game, and to be fair to them, they really do look after you when you're dealing with things like that."
