Three costly Man Utd errors led to their first PL defeat of the season including two surprise substitutions - view

Manchester United were undone by a series of costly mistakes that ultimately handed Brighton & Hove Albion a memorable victory.

A dramatic 95th-minute strike from Joao Pedro proved to be the difference with the South Coast club taking all three points.

Former Red Devil Danny Welbeck tapped in from close range for Brighton in the first half. Amad Diallo brought United level with a deflected shot.

Both teams were vulnerable in the later stages of the clash in search of the winning goal.

The home side took the points, ensuring a perfect home start for their new manager Fabian Hurzeler.

We look at three mistakes that combined to derail United’s ambitions and allowed the Seagulls to secure a victory.

Losing focus in defence

The Red Devils made several mistakes in defence last season. They often leaned on the excuse of an injury-ravaged defence to deflect criticism for their defensive frailties.

That safety net has been pulled away after the business done this summer window.

Harry Maguire kept his starting spot alongside Lisandro Martinez at the back.

The England international put up an impressive showing against Fulham but he let himself down yesterday.

He had two opportunities to avert disaster but hesitated which helped Welbeck open the scoring.

A more proactive defender would have intercepted the cross or booted it away.

Martinez didn’t cover himself in glory either as he should have marked the striker better.

The whole United defence switched off in the 95th minute. As they fixated on Simon Adingra, they completely overlooked Pedro lurking unmarked at the back post.

The 22-year-old had all the time in the world to direct his header far enough from Andre Onana’s reach and seal a dramatic win for Brighton.

Not allowing Garnacho to come in at half-time

Erik ten Hag made plenty of game-management errors last campaign. He started his count yesterday for the new season.

The Dutchman wants to support Amad Diallo by starting him on the right flank.

Considering Alejandro Garnacho was not involved in pre-season, he wants to slowly integrate the winger back.

With United 1-0 down at the break, Ten Hag should have unleashed Garnacho.

The Argentine showed his class in his cameo against Fulham, delivering the match-winning assist for Joshua Zirkzee.

Ten Hag chose to hold off until the 65th minute before responding to the growing clamour from United supporters to bring Garnacho on.

He made an immediate impact, brilliantly slotting the ball into the net.

However, the jubilation was short-lived as his goal was ruled offside. Zirkzee’s touch on the ball before it went in was decisive.

Subbing Bruno Fernandes off

As the game approached the final 10 minutes, it was surprising to see Bruno Fernandes make way for Scott McTominay.

Removing your most creative player in the crucial minutes of the game proved to be a disastrous decision from Ten Hag.

Fernandes may not have been at his best, but his struggles were partly due to being deployed as a false nine.

After Zirkzee came on, Fernandes moved to his usual number 10 position and his involvement grew.

He played a delightful pass to Garnacho for his ruled-out strike.

McTominay’s substitution had little impact on the attack as he is typically more effective at finishing chances rather than creating them.

With Fernandes off the field, United lost their primary playmaker and catalyst.