A mixture of defensive ineptitude and Brentford’s superior strategy saw United concede four goals at halftime.
Their nightmare began in the 10th minute when United keeper David de Gea allowed a weak shot by Josh Dasilva to slip past him. Things got worse eight minutes later when De Gea played the ball out to former Brentford player Christian Eriksen who was caught in possession and Mathias Jensen slotted home.
Ben Mee glanced in a close-range header to make it 3-0 before Ivan Toney delivered a diagonal ball to Bryan Mbeumo from a counter-attack and Mbeumo calmly beat De Gea.
Ten Hag had insisted before the game that he was not panicking despite United’s lack of new signings but the Dutchman must be panicking, coming a week after a 2-1 home loss to Brighton.
To top it all, United sunk to the bottom of the table for the first time in 30 years.
Player ratings from the match can be seen in the picture gallery above. To view the next image, click on the arrows or swipe if on a mobile device.