CASEMIRO was slammed by Manchester United fans after unforgivably playing Arsenal onside for their opening goal at Old Trafford.

Erik ten Hag’s men fell behind midway through the first half on Sunday when Kai Havertz laid the ball across for Leandro Trossard to tap home from close range.

Casemiro, far left, did not run out when Andre Onana cleared away

When the ball was played to Kai Havertz, Casemiro was clearly playing him onside

Trossard tapped home to give Arsenal the lead

Casemiro has endured a nightmare season at Old Trafford

But Havertz was only in an onside position because Casemiro had failed to get back in line with the rest of his defence when keeper Andre Onana cleared away.

The Brazilian, 32, who endured a nightmare at Selhurst Park in Man Utd’s 4-0 defeat over Crystal Palace on Monday, then watched as the ball fizzed past him to Trossard – who broke the deadlock with ease.

And those on social media were quick to lament the midfielder’s position in the lead-up to the goal.

One said: “Wow. Casemiro just trotting up the pitch. Absolutely comical defending.”

Another added: “Casemiro and Evans backline gotta be the lowest point of my Manchester United supporting life 😭😭😭😭.”

A third replied: “That’s first on Casemiro. Played Havertz onside with that sluggish jog out of his box. And then on Wan Bissaka who completely lost Trossard.”

A fourth responded: “This Casemiro downfall needs to be documented, this is absolutely horrendous.”

While a fifth said: “Brother he’s pushing 40, Madrid scammed United.”

Meanwhile, Man Utd icon Gary Neville agreed with the criticism of Casemiro as he tore him apart on commentary.

He said: “Casemiro has got some criticism recently and he’s going to get a little bit more.

“Brilliant from Arsenal, those Arsenal fans in the corner recognise it’s been a difficult 20 minutes.

“As soon as he goes past Amrabat, Casemiro has to get up. Look at him jog, you see that ball being played and, once he doesn’t he is in trouble.

“Trossard does what every good wide player does, makes that diagonal run inside the full back, Wan-Bissaka is caught out and it’s a simple one in the end.

“Casemiro’s experience in the game, he must have seen the ball had broken down and where Havertz was, he had to get up that bit quicker.

“There’s no doubt it’s not going to be easy for him. Before in the studio they said he needed protecting more, he’s actually had that.

“That is a basic error. You have to get up quicker and he ambles out and there is no excuse for that.”

On Friday, Casemiro was dropped from Brazil’s squad for this summer’s Copa America.