Manchester United put in one of their worst performances in 30 years of the competition as they were thrashed by Brentford.
In an astonishing first half in some intense west London heat, goalkeeper David de Gea let Josh Dasilva's simple shot crawl under his body at the near post after 10 minutes before the goalkeeper's pass put Christian Eriksen in trouble.
The Bees took a 2-0 lead into the half-time break, with Ben Mee leaping over Lisandro Martinez to head home his home debut, before Ivan Toney fed Bryan Mbuemo to complete the scoring.
The result leaves ten Hag's side bottom of the league with zero points, with their next opponents at Manchester United on Monday Night Football.
From the beginning of the game, United's problems were obvious. The intense heat that hit west London on the day of the game left De Gea red-faced.
Dasilva tried to shoot with his weaker foot but De Gea couldn't block it. Ten Hag tried to play out from the back but couldn't stop them from getting them.
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The No 8 set himself before rolling the ball past a wrong-footed De Gea after Eriksen was stopped by Jensen in the penalty area.
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Even with the recalledRonaldo starting up front, United's attack produced very little to test David Raya. Raya let the fly harmlessly over his bar after the 37 year old produced a couple of snapshots.
After just 35 minutes, the game was beyond United. The debutante showed more determination than the Spaniard to nod in the corner.
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As United tried to get back in the game, they were hit on the break by the Bees. Toney sprinted away to find Mbuemo in the middle, who hurdled a challenge from Shaw to steer the ball past De Gea.
There was a triple substitution at the half-time break. There were some improvements after the break.
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As Dalot found him twice in a lot of penalty area space, he had two excellent chances to pull a goal back, but he headed over.
As he headed straight at Raya, he tried to pull a shot from inside the box, but it was too little, too late. After the first half, United didn't need to get out of second gear.
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Sky Sports' Sam is at the stadium.
They've spent most of the summer waiting to see if he'd come back or if they'd find a replacement. They signed Mikkel Damsgaard on Wednesday and moved on from the Danes that kept them up.
What do you think about that performance? He went from being a club icon to being involved in an embarrassment.
The quality of play between the two teams is not the same. Raya looked like he knew what he was doing at all times. The presence of Pontus Jansson and Ben Mee made a difference in the fight. The finishing was clinical that could not be done by the others.
In the middle of the field, it was where United were attacked. The normally-attacking Fred was set up with Ten Hag at the base. Dalot and Shaw came into the middle of the field to support them.
The chalk and cheese fight was in the middle. Fred was taken off at the half-time break because he couldn't protect the back four. The chances that Jensen and Dasilva could could not be compared to the one that Eriksen played in.
The two teams are compared more than just on the field. In order to find gems like Jensen and Mbuemo, they use a specific recruitment scheme.