Adelaide midfielder Isaias Sanchez was sent off just 10 seconds into the second half of his team's embarrassing 4-0 loss to Central Coast in Gosford.
The Mariners led 1-0 at halftime of Saturday's A-League Men match courtesy of a Alexandar Popovic own goal, but it completely unravelled for Adelaide after the break.
Isaias was given his marching orders immediately after the restart when he unleashed a dangerous swinging leg tackle from behind on Jacob Farrell.
The floodgates opened after that as Central Coast slammed through three goals in the next 12 minutes.
It would have been even worse if not for Samuel Silvera's 66th minute strike being rubbed out by VAR after a teammate was ruled offside.
Adelaide's worst-ever loss remains a 7-1 defeat to Brisbane Roar in 2011 when Besart Berisha scored a first-half hat-trick on the way to four goals for the match.
But Saturday's result felt just as deflating as the Reds produced arguably the worst second half in the club's history.
Central Coast's fourth straight home win lifted them into second spot on the ladder, while Adelaide slipped to fifth and are in danger of dropping further after winning just one of their past five matches.
"Everybody writes us off," Mariners coach Nick Montgomery said when asked if his team can go all the way this season.
"They wrote us off last year, they wrote us off at the start of this season.
"It's no secret, we're the youngest team with the smallest budget in the league. But that's what this club is about - it's about being the underdog and rising above it."
Adelaide's defence held firm until the 31st minute when Silvera, filling the void left by the departed Garang Kuol, unleashed a curling strike from outside the box.
The ball appeared set to miss the target, but it deflected off Adelaide defender Popovic and into the back of the net.
Adelaide's victory hopes evaporated following a brain fade from Isaias immediately after halftime.
"We have been quite harsh on any studs making contact. I haven't agreed with a lot of them," Adelaide coach Carl Veart said of the incident.
"That's something that we, as a league, are a lot tougher on than anywhere else in the world."
Two minutes after the red card the scoreboard read 2-0 when Beni N'Kololo fired in from close range after great lead-up work from Silvera.
The humiliation continued when Panashe Madanha became the second Adelaide player to score an own goal, with the ball bouncing in off his legs after a save from goalkeeper Joe Anthony Gauci.
And it was 4-0 in the 58th minute when Silvera skipped past Juande to set up Farrell for a goal.
"For us, it's one to clear from the mind and to forget as soon as possible," Adelaide skipper Craig Goodwin said of the horror result.
