Complacent Man Utd could RUIN their season by failing to kill off teams - their capitulation against Sevilla must be a warning sign for Erik ten Hag

Complacency could be seen in how United failed to score a third goal after taking a 2-0 lead after 21 minutes thanks to Marcel Sabitzer's sharpshooting.

Although Antony came agonisingly close to scoring, hitting the inside of the post, there was an overall lack of urgency from United's attackers in the second half.

Wout Weghorst had the chance to turn and shoot at goal inside the area but instead played the ball back to Tyrell Malacia, who was in a worse position and further from goal.

The Dutch defender had four players in his way and his shot was blocked.

Complacency could also be seen in United's slack marking from the corner before half-time, when David de Gea clawed a Tanguy Nianzou header into the air and Raphael Varane had to scramble it off the line.

The Frenchman was forced off injured immediately after the action and had to be replaced by Harry Maguire, who ended up getting the final touch on Sevilla's equaliser.

By far the worst example of United's carelessness was how Malacia let the ball go behind him without looking to see if there were any Sevilla players near him in the build-up to their first goal.

He had failed to sense the presence of Jesus Navas, who was part of Sevilla's first two UEFA Cup wins in 2006 and 2007 and embodies the team's never-say-die attitude which has helped them win this competition a record six times.

The 37-year-old pounced and Malacia was too slow to react properly, sending the ball past De Gea, who was also taken by surprise.

Malacia's attitude was the epitome of complacency. Perhaps the two-goal cushion made him think he did not have to fight for every ball any more.

But his mistake woke the beast of Sevilla and suddenly United were not so confident.

Sevilla coach Jose Luis Mendilibar, a veteran of La Liga but who was taking charge of his first proper European match at the age of 63, spoke of how United took their foot off the gas and lost their nerve.

"Bit by bit they stopped creating as much danger, we didn’t suffer as much as we did in the first half," he said.

"They became scared once we equalised and were nervous towards the end."

Mendilibar even felt that his side's reputation in the Europa League played on United's minds.

"People respect Sevilla in this competition. When Man Utd were playing well, it was very easy for them, they scored two goals and could have scored more but when Sevilla pushed up forward I think they felt our presence in there," he said.

"All the teams respect Sevilla a great deal in this comp and that is what we try to take advantage of as well.

"In this competition, Sevilla have that soul, they believe in this competition and they believe in what we want to do."

Paul Scholes was in no doubt that United got too comfortable.

"A really strange second half that you can only put down to complacency," the former United midfielder said.

And he said Ferguson would never have allowed the team to lose focus as Ten Hag's side did.

"Did it happen when we played? Possibly, but I don’t think the manager would have allowed us to be complacent in the second half. When you’re in a quarter-final like that, that’s the time to win the game, to win the tie. You win it here tonight.

"That should be 3,4,5-0 tonight against the opposition you’re playing. The only thing I can think, they felt it was going to be too easy, they felt it was going to be a stroll in the park.

"You just can’t do that in European competitions, you can’t do that against a club like Sevilla."

The Sevilla game was the most blatant display of United's complacency but they have been guilty of not finishing teams off on numerous occasions this season.

They failed to see the game out away to Crystal Palace and conceded a late equaliser from Michael Olise's brilliant free-kick.

And although they were often the second best team in their 3-2 defeat at Arsenal, they still only lost because they let in a 90th-minute header from Eddie Nketiah.

Even when they have ended up winning games, there has been a sense that they made things hard for themselves.

Take last Saturday's win over Everton, when they outplayed Sean Dyche's side and had 20 shots in the first half but only had one goal to show for it after big misses by Antony and Marcus Rashford.

They were made to battle for their 2-0 win and their efforts may have played a part in Rashford injuring his groin and being ruled out for the next few matches.

The sense of anxiety they felt after conceding the first goal against Sevilla may also have been a factor in Lisandro Martinez's nasty-looking injury.

Had United got a third goal midway through the second half, they could have afforded to rest players for the second leg at the Sanchez Pizjuan.

But now Ten Hag will not be able to afford that luxury, and the injuries to Varane, Martinez, Rashford and Luke Shaw make their task in Spain next week even harder. They will also miss Bruno Fernandes due to suspension.

The injury pile-up also means the manager has no option but to pick most of his bedraggled players again for Sunday's trip to Nottingham Forest, which is crucial in the race to finish in the Premier League top four and return to the Champions League.

The one positive is that hopefully what happened on Thursday should mean they do not rest on their laurels again, and kill off their opponents when they have the chance.