Manchester United’s late 1-0 win over Fulham in last Friday’s season opener showed concerning similarities with last year’s travails. Better were the crisp phases of passing and intelligent movement during the first half, but then came a falling away of shape, of dismal finishing – Bruno Fernandes being a chief culprit – and the reliance, again, on a moment rather than in-game domination to claim victory: the substitute Joshua Zirkzee’s deft 87th-minute strike finally beating Bernd Leno.

For the young Dutchman a dream start after his £35.8m transfer from Bologna. For his compatriot Erik ten Hag, the contemplation of more unwanted forward line profligacy, summed up by a pithy post-match demand that his charges “kill in the box”, and the hope that at Brighton in Saturday’s 12.30pm kick-off the team will finally click and show they can be a formidable unit this campaign. The trip to the south coast is a test. Fabian Hürzeler’s men are coming off the 3-0 hammering of Everton at Goodison Park – the very best of beginnings for the Seagulls under a new manager who does not turn 32 until February.

Related: Premier League: 10 things to look out for this weekend

Ineos’s first summer market at United has yielded Zirkzee, two centre-backs in Matthijs de Ligt and Leny Yoro plus a full-back in Noussair Mazraoui. Starting in the right-hand defensive berth on debut Mazraoui appeared accomplished, though he needs to eradicate the odd loose pass to the opposition that could be costly on other days.

As an 81st-minute substitute against Fulham, De Ligt had constricted time to show anything revelatory about his worth so Saturday’s teamsheet will be intriguing in regards to discovering if Ten Hag has found the 25-year-old a place in his starting XI, which would almost definitely mean dropping Harry Maguire, who after the win against Fulham insisted he feels fit. “Physically and mentally, I’m in a good place. I’m looking forward to a big season,” said the 31-year-old, who was an eye-catching package of aggression, leadership and decisive interventions on the opening night.

The suspicion remains that Maguire will be the fall guy for De Ligt, and if not at Brighton, then soon. But his value to Ten Hag has increased after Yoro was ruled out for three months. Maguire is one-paced and can be error-prone but his attitude is inarguable, as shown by his fight to again be a factor after being bombed out of the side by Ten Hag two seasons ago.

The wider picture for United’s manager at the Amex Stadium concerns a question of strategy. Persist with Fernandes as the false No 9, deploy Marcus Rashford there or draft in Zirkzee from the start? Last season Ten Hag’s six-man strike coterie of Rashford, Rasmus Højlund, Jadon Sancho, Amad Diallo, Alejandro Garnacho and Antony returned only 26 goals from a paltry 57 managed by the entire squad in the Premier League. Højlund led with 10 in 30 appearances. Like Yoro, the Dane went down in pre-season and is out for about another month. Zirkzee was bought to support and compete with the Dane, which proved prudent after the latter’s injury.

If Ten Hag starts Rashford at No 9, can he prosper in a role he seems built for? Lightning fast, tall, and a killer finisher when the mood takes him, Rashford could be one of the era’s fine central forwards except his preference is to launch raids from the left.

The 26-year-old scored 30 from that role two seasons ago – Kylian Mbappé apart, no other winger on the continent can boast those numbers in recent years.

Sancho missed the win over Fulham because of an ear infection but Ten Hag, asked about his availability for Brighton, chose to deliver a sermon about rotation and attitude. Again, intrigue centres on the manager’s selection to face Brighton: will Sancho, exiled from the squad last season, even make the 20-man matchday squad?

The 24-year-old may still depart Old Trafford as he competes with Amad (who was impressive against Fulham), Garnacho, Rashford and Antony: the odd man out, perhaps, in a quintet vying for the two wide berths, with Ten Hag stating he wants “double positioning” throughout the team.

Where United lack depth is in central midfield. Kobbie Mainoo is nailed on to start as a box-to-box schemer but Casemiro at the age of 32 cannot, surely, last the slog of a domestic and Europa League campaign. Paris Saint-Germain’s Manuel Ugarte, a holding operator, is being pursued to fill this void. United are confident he will be recruited. If so, the tilt at a top-four finish – or better – will be bolstered, as Ten Hag also bids to add a third piece of silverware in a third season, after Carabao Cup and FA Cup triumphs.

Maguire says: “Obviously we want to be in the Champions League spots. We missed out this season as we weren’t good enough in the league. This club demands trophies. So we want to win another trophy and in the Premier League we know there’s large improvements that we need to do and make from what we did last season. For sure, we’ve got to improve on last season and let’s see where it goes and takes us.”