OK, Manchester United fans - NOW you can panic.
Because Erik Ten Hag, whatever he says publicly, must be.
There were still more than five minutes to go in surely the first half of football ever played by a United team, when the visiting fans struck up what is becoming an all-too-familiar chorus.
“You’re not fit to wear the shirt,” they sang. And when that shirt is the hideous new green one they were sporting for the first time, that’s saying something.
Back in the good old days, Sir Alex Ferguson ordered his team to ditch their hard-to-pick-out grey kit when they trailed 3-0 at half-time to Southampton.
But a game that ended in a 3-1 defeat back in April 1996 did not stop United going on to win the Double.
Only two games into this campaign, and you can be sure that won’t be happening this season or for the foreseeable future.
That is to take nothing away from Brentford.
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The Bees were Thomas Frankly brilliant and ruthless in putting Ten Hag’s men to the sword.
Josh Dasilva, Mathias Jensen, Ben Mee and Bryan Mbeumo scored the four first-half goals for a home side that was superior in every department.
But United were the architects of their own downfall.
David De Gea was at fault for the opening two goals.
After letting Dasilva’s shot go through him for the first, he played Christian Eriksen into trouble for the second on a very unhappy return for the Dane to the club that helped his resurrect his career.
United teams of the past, when the heat was on, would have stayed cool and plotted a way back into the game.
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This dismal crop wilted in the West London heat like a bouquet of cheap flowers from a garage.
The big difference being, of course, that United have spent hundreds of millions assembling this motley crew.
And they will have to spend hundreds of millions more to have any chance whatsoever of returning to where they believe they belong.
Of course, Ten Hag deserves time to try to succeed where everyone since Ferguson has failed.
But if he is having as much say in the transfer policy as is believed, then he has to take some responsibility for his predicament.
After the historic, limp home defeat by Brighton, the only significant change he could make was to restore Ronaldo to the starting line-up.
Ten Hag brought in the man who wants out for Scott McTominay.
The United fans who had been calling for the break-up of the McFred midfield partnership were thereby granted their wish.
Eriksen, booed gently throughout, found himself alongside Fred as (presumably) a deep-lying midfield creator. Six days earlier against Brighton, he had begun the game as a false nine.
Whether the change in role said more about the Dane’s versatility or the general confusion at United, remained to be seen. But not for long.
Brentford boss Frank rewarded Dasilva for scoring the equaliser in the 2-2 draw at Leicester by bringing him in for Yoane Wissa.
That faith was repaid inside 10 minutes.
Ronaldo dropped deep to receive a throw-in, lost the ball and was clutching a calf as the nightmare unfolded.
Dasilva charged forward then hit a shot from just outside the box that looked too tame to trouble a goalkeeper of De Gea’s quality. But he let it slip through his hands and inside his left-hand post.
Things soon got even worse for him and United.
After Jensen had sent a free kick just over the bar, United took the goal kick short to De Gea.
His hospital pass to Eriksen was pounced on by Jensen, who rolled the ball calmly into the net.
The Brentford fans were soon telling Ten Hag he would be sacked in the morning.
When Mee made it three, you wondered if the United board should wait that long.
Those who had questioned the wisdom of signing a 5ft 9in centre half had their “told you so” moment.
Lisandro Martinez could do nothing to stop Mee heading in from close range after Ivan Toney headed Mbeumo’s corner back across goal.
The home supporters had barely finished asking Eriksen what the score was - for the first of many times - when, incredibly, their team scored a fourth.
Christian Norgaard hit a long ball from his own box into the left channel.
Toney hit a wonderful first-team pass into the path of Mbeumo as he left Luke Shaw puffing in his wake, and the Brentford striker provided the finish worthy of the move.
It was just the sort of goal you would expect a front four like Ronaldo, Jadon Sancho, Bruno Fernandes and Marcus Rashford to score.
But they were nowhere to be seen, utterly ineffective and impotent.
Little changed after the break going forward, although Ten Hag’s triple change at the break at least made United more secure at the back.
After De Gea stopped Aaron Hickey making it 5-0, Ronaldo sent two headers off target and reacted with theatrical disappointment.
The home crowd cheered loudly when Eriksen saw a header saved, then hit a great chance wide and, finally, as he was substituted.
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“You should have stayed at a big club,” they told him earlier in the game.
How the mighty have fallen.