Carlos Baleba was paraded on the pitch before kick-off on Sunday and Old Trafford got its first glimpse of Manchester United’s other two big summer signings, Andrey Santos and Youri Tielemans, in action against Ipswich.

Aside from bringing in new back-up goalkeeper Karl Darlow as a free agent, midfield has been the priority project for United in this transfer window, a year after they reloaded the attack with Benjamin Sesko, Bryan Mbeumo and Matheus Cunha. More than £360million spent on improving two areas of the team.

The plan, it’s understood, was to leave the defence until next summer when Luke Shaw, Harry Maguire and Lisandro Martinez will be out of contract. Decisions will have to be made about those players – United have the option to keep Maguire and Martinez for an additional 12 months – and some of the club’s other defenders.

However, after the 5-2 win over Ipswich was dominated by Bruno Fernandes’ hat-trick, Marcus Rashford’s Old Trafford return and Kobbie Mainoo sparkling in the new midfield order, there was no ignoring the nagging concern that United cannot afford to wait so long to strengthen at the back – and, above all, at left back.

Shaw has experienced his fair share of ups and downs over a 12-year career at Old Trafford that makes him United’s longest-serving player by some distance. Still only 31, he exceeded all expectations last season by starting every Premier League game for United.

But after a summer in which he was left out of England’s World Cup squad, Shaw has had a bumpy start to the new campaign. On Sunday, he was left trailing in Abdul Fatawu’s wake as the Ipswich winger set up the opening goal for Leif Davis.

Luke Shaw was left trailing in Abdul Fatawu’s wake as the Ipswich winger set up the opening goal for Leif Davis on Sunday

Manchester United’s initial plan was to revamp their defence next summer, when Harry Maguire (centre) and Lisandro Martinez (right) will be out of contract 

After losing their first game of the season at Hull, United were able to recover against another of the newly promoted teams and win handsomely on this occasion, but the question mark over Shaw lingered. Afterwards, he admitted it wasn’t good enough and said he is expecting some new signings before the window closes.

‘I’m disappointed in myself,’ Shaw admitted. ‘With my experience, I must be doing much better for the first goal – that’s not me. We showed the right mentality. It’s never nice to lose the first game when everyone is so optimistic, but we’ve got a lot of experience to block out the noise.

‘The objective has to be to win the Premier League, and last week’s result doesn’t mean we can’t do that. I’m sure there will be a couple additions to the squad which are needed to make us stronger.’

Will United use deadline day to sign a new left back? The word from inside Old Trafford is that the club are open to doing so if the right opportunity comes along, but there is no guarantee it will happen. Of course, director of football Jason Wilcox and the recruitment team led by Christopher Vivell have been aware of the issue all summer, even more so after the rarely used Tyrell Malacia left as a free agent.

It’s why United have maintained an interest in Lewis Hall throughout, while reluctantly accepting that it would be a difficult deal to execute in this window when so much of the budget has been committed to the midfield rebuild. Newcastle are determined to keep hold of Hall after selling Anthony Gordon, Sandro Tonali and Bruno Guimaraes, and it would take a bid of more than £75million to make them even consider letting the 21-year-old leave Tyneside.

Unless United can come up with that kind of money before the window closes at 11pm on Tuesday, the club will have to postpone any bid for Hall – as they did with Baleba, signing the 22-year-old Cameroon international for £70million a year after being put off by Brighton’s demand for £100million-plus.

But then what? It would seem reckless to head into the rest of a busy season that sees Michael Carrick’s team back in Champions League action without bringing in competition – or at least cover – for Shaw. Even if he regains his form and stays fit, it’s asking too much of him to start every game again – especially as United will have to play significantly more matches this season than the 40 (also known as the bare minimum) of last season.

United are believed to have assessed other options besides Hall, including Brighton’s Ferdi Kadioglu, Ian Maatsen of Aston Villa and Racing Santander’s Jorge Salinas.

United are in for Newcastle’s Lewis Hall, but it would take a bid of more than £75million to make them even consider letting the 21-year-old leave Tyneside

Brighton full back Ferdi Kadioglu (centre) is also on United’s list if they cannot convince Newcastle to sell Hall

Racing Santander’s Jorge Salinas is another player United have assessed

Perhaps their best bet as the clock continues to tick down is a loan deal. United have looked at Barcelona’s Alejandro Balde, but their options are limited at this stage of the window. So too, however, are the alternatives if no deal can be done. Right backs Diogo Dalot and Noussair Mazraoui are both capable of switching to the left, where Mazraoui plays for Morocco.

Patrick Dorgu was signed as a left wing-back but has performed better in a more advanced position. Academy graduate Harry Amass was Shaw’s understudy in pre-season and could continue in that role if United decide to keep him. Martinez has also played there and Baleba, a left-footed defensive midfielder, has even been mentioned as a makeshift left back.

But if United have genuine title aspirations, as Shaw says, it seems like an unnecessary gamble not to sign another specialist defender in his position.

The bulk of United’s defensive overhaul will have to wait until next summer, even though conceding two set-piece goals in the opening-day defeat at Hull was alarming, and Martinez was punished for his sloppiness when Ipswich scored their second goal on Sunday. On the evidence of that game, attack may be United’s best form of defence this season.

The only other potential business at Old Trafford on deadline day would be a replacement for Joshua Zirkzee if the Dutch forward returns to Italy. Otherwise, all eyes will be on left back and whether United stick or twist.