The assistant referee's flag was already raised for offside when Arsenal striker Pierre-Emerick Aubameyang chipped a deft finish past United goalkeeper David De Gea in the 58th minute of a frenetic and error-strewn Premier League game between the two old rivals on Monday.
When the goal was reviewed by VAR, the replay showed Aubameyang was clearly being played onside by United defender Harry Maguire, directly in front of the assistant referee. The decision was overturned and Arsenal had its equalizer in 1-1 draw at Old Trafford.
United manager Ole Gunnar Solskjaer complained to the fourth official in the technical area, saying the referee had already blown his whistle before Aubameyang took his shot. De Gea said after the match that he had been distracted by the on-field call.
"Of course," the goalkeeper said. "It's easier if the linesman keeps the flag down."
The complaints cannot change the fact that United, the most prestigious team in England, is languishing in 10th place and has fewer points — nine — after seven games than in any season since 1989. It has not scored more than one goal in any of its last seven matches in all competitions.
"This is Manchester United, so we have to win these games," De Gea said. "The lads have to react and play better than they are doing."
If only United had a striker as clinical as Aubameyang, who became the first Arsenal player to score seven goals in the first seven games of a Premier League campaign since Dennis Bergkamp in the 1997-98 season.
His only real chance of the game came out of nothing, with United defender Axel Tuanzebe giving the ball away with a misplaced pass in front of his own area. Bukayo Saka played a first-time pass forward to Aubameyang, who cut inside and applied the finish.
"I was sure I was not offside. I was surprised the referee whistled," Aubameyang said. "I always try to score even if there is a whistle from the referee."
It canceled out United's opening goal by Scott McTominay in first-half stoppage time, the midfielder's shot from the edge of the area taking a slight deflection off the shoulder of Arsenal defender Sokratis and flying into the roof of the net.
United finished the stronger, with Paul Pogba curling a shot just wide and McTominay heading over from a corner when unmarked in front of goal.
Still, it was yet more disappointment for Solskjaer, who has won just four of 15 league games since being hired on a full-time basis in March.
"We need to be more cynical, clinical, at both ends of the pitch. We'll learn," Solskjaer said. "I thought today we are going somewhere."
Traditionally one of the biggest matches in English soccer, this Man United-Arsenal fixture pitted the teams in 11th and eighth places, respectively, at kickoff. Indeed, United had never been as low down the standings heading into a match against Arsenal in the history of the Premier League.
The poor quality on show highlighted how far the teams had fallen, with a slippery surface on a wet night in Manchester hardly helping.
"Thoughts on the game so far without using a bad word?" former Arsenal midfielder Cesc Fabregas tweeted during the first half. "Try to be creative."
Even United's goal in first-half stoppage time had a touch of the farcical about it, with Granit Xhaka — Arsenal's recently confirmed full-time captain — ducking his head as McTominay took aim and the ball flying past him and high into the net.
It meant the game opened up in the second half, with Arsenal committing more players forward and showing more intensity with their pressing.
Still, that can hardly excuse Tuanzebe, filling in out of position at left back in his first league start for United since May 2017, for his misplaced pass that led to Aubameyang's equalizer.
It was enough to lift Arsenal into fourth place, above West Ham on goal difference.
"I want more," Arsenal manager Unai Emery said. "More in the result and in the performance, but we are progressing."