Man Utd have been left exposed: Lack of defensive midfield signing threatens to cost Erik ten Hag a triumphant second season

Ten Hag lined up against Wolves with more or less the team he had been picking in pre-season, but once the game kicked-off, Luke Shaw was inverting from left-back and joining Casemiro in holding midfield. The idea was to give the team the 'box midfield' that has became fashionable among Premier League sides since Pep Guardiola began using it last season.

The experiment did not go well, though, as Lisandro Martinez struggled as a left-sided centre-back in what had become a back three, while Alejandro Garnacho had no support behind him on the left wing. The shape was abandoned at half-time, with Shaw moving back into left-back, leaving Casemiro badly isolated in holding midfield.

Too often Casemiro was the one under pressure. As Gary Neville put it on Sky Sports: "Casemiro got absolutely torn to shreds tonight. Manchester United's midfield were non-existent and they were absolutely ripped apart... It emptied. That would have been a real worry for Erik ten Hag."

Mason Mount, United's £60m ($76m) signing from Chelsea, was placed alongside Bruno Fernandes ahead of Casemiro and offered very little defensively. Indeed, he nearly gave away a chance after mis-controlling a pass from Onana, having to be bailed out by Casemiro.

The England midfielder hardly compensated in attack and his dire stats during his 68 minutes on the pitch were widely shared online after the game. As well as scoring no goals and providing no assists, he created no chances, made no crosses, won no tackles nor any aerial duels.

Mount's signing for United baffled plenty of fans, as attacking midfield did not seem to be a priority position, while a box-to-box midfielder or back-up to Casemiro would have been more useful to the squad. Ten Hag has spoken about his plan for Mount to be "multi-functional" and contribute more defensively, but on Monday's evidence, that plan needs a lot more work.

United have already parted ways with one half of the dreaded 'McFred' partnership which made up their midfield for the best part of four seasons after selling Fred to Fenerbahce. Scott McTominay remains, however, and United rejected a £30m ($38m) offer from West Ham for the Scotland international earlier in the summer.

Ten Hag, however, does not seem to trust McTominay enough to start him regularly. He handed him only 10 Premier League starts last season and put him on for just two minutes against Wolves. McTominay is hard-working and offers a goal threat, but he does not have the technical ability that playing midfield for United demands.

He struggles under pressure and is not particularly strong at bringing the ball forward over long distances, while his passing range is nothing special. He also struggles with niggling injuries, preventing him from getting a solid run of games.

"One thing that Erik ten Hag is not going to do is go back to the likes of Fred and Scott McTominay, who he believes are technically not good enough on the ball," Neville added. "He wants everybody in the team to be able to accept the football and receive it."

Neville believes Sofyan Amrabat would help solve United's midfield problems. United have shown interest in the Morocco midfielder, who was one of the stars of the 2022 World Cup, throughout the summer, but have yet to make an official bid to Fiorentina.

Amrabat, 26, has the power and tenacity of Casemiro but is also both a fine dribbler and passer, and would definitely be an upgrade for United. He is keen to leave Fiorentina and has not played in any of their pre-season matches. United cannot afford to sign him for now, however, as they are teetering on the edge of the money they are permitted to spend due to the Premier League's Profitability and Sustainability rules.

The only route towards Amrabat - or Everton midfielder Amadou Onana - is to sell players to free up not only transfer budget but also places in the squad. Fred, Anthony Elanga and David de Gea are the only players to have left so far, and the latter departed as a free agent.

The collapse of Harry Maguire's proposed £30m move to West Ham delivered a blow to United's ambitions to bolster their squad, while there have been no takers for Donny van de Beek or Anthony Martial. And United's struggles to raise cash have now led to Liverpool entering the race for Amrabat.

United only began to get a foothold against Wolves when Christian Eriksen replaced Mount. The Dane was able to calmly deal with pressure and help his side hold on to the ball for longer to keep the visitors at bay.

Eriksen played a key role in United's revival last season and formed their best midfield trio alongside Casemiro and Fernandes. He was also sorely missed when he was out for two months with an injured ankle, but Eriksen tired as the punishing season wore on and he was often the first player to be substituted.

He is 31, like Casemiro, and it began to show, especially against Manchester City in the FA Cup final, when he was badly exposed by Kevin De Bruyne and Ilkay Gundogan. The idea that he is the best short-term solution to United's midfield issues says a lot about how much they overlooked such a key area in the summer.

Ten Hag has had four days to find a solution to his team's midfield woes before United's next fixture, and can expect both Tottenham on Saturday and Arsenal in just over two weeks' time to put his side under even more pressure than Wolves did in the middle of the park.

James Maddison had a fine debut for Tottenham, providing two assists in the 2-2 draw at Brentford, and will be one of the players United will be keenest to shackle. Yves Bissouma was also excellent in the holding role.

The trip back to north London is even more daunting. The Gunners did not get off to the brightest of starts against Nottingham Forest, but Gabriel Martinelli and Bukayo Saka were in sparkling form and are unlikely to be as wasteful as Cunha, Sarabia and Neto.

United's away form last season against the top half of the table was horrendous, with Tottenham and Fulham being the only teams who finished in the top 10 who did not beat Ten Hag's side on home soil. And unless the Dutch manager can get a grip on his midfield or pull a rabbit out of the hat in the transfer window, his side could have some more long journeys home coming up.