After the relief of an opening-day victory for Manchester United, the manager Louis van Gaal admitted he may yet buy a forward and a central defender. The way his team laboured to a 1-0 win over a fitful Tottenham Hotspur illustrated why. The 4-2-3-1 he fielded again lacked spark in attack and was shaky when the visitors came at them.

That was the story of the club’s summer tour of the US. In the four warm-up matches there, United were walked through on occasion and struggled to create chances for Wayne Rooney. The captain is the lone elite striker in the squad and he rarely troubled Mauricio Pochettino’s team during a contest played in blazing Manchester sunshine.

The exception was United’s 22nd-minute winner. Clear in on Michel Vorm’s goal, Rooney was about to pull the trigger when Kyle Walker did it for him, with the right-back inadvertently finishing beyond his own goalkeeper.

Before this Harry Kane had easily unlocked United’s defence with a looping ball that gave Christian Eriksen a gilded chance to beat the debutant goalkeeper, Sergio Romero, but the Dane missed.

Barcelona’s Pedro, who has a £22m release clause, and Real Madrid’s Sergio Ramos, still head the list of players Van Gaal favours and the manager is clear he is only interested in exceptional players.

“No, that is not a special item for me, it is more in the media they are discussing about a striker,” said Van Gaal. “The striker is Wayne Rooney and we also have [Javier] Hernández, [Adnan] Januzaj and [James] Wilson. It is not a special objective for me. But when we can buy another striker who has a lot of qualities, more than our players, then we buy. But we have always done that. I said it before but they [the media] are not writing it. I have said it before, we have Rooney. You [the media] said he has to play in a striker’s position.”

Phil Jones was absent because of a mild thrombosis that rules him out for at least three weeks. Despite his unavailability and Van Gaal questioning the right side of central defence after United’s 2-0 loss to Paris Saint-Germain in the final US tour game, the manager struck the same note about the position.

“No we have three centre-backs, we have [Paddy] McNair, Jones and [Chris] Smalling but if he [a new centre-back] is much better than them, then it is possible. We go for the best players and it has to be possible,” the 64-year-old said. Against Spurs, it was Smalling who operated alongside Daley Blind.

Pedro would offer another option in attack. Yet the Spaniard is no leader of the line. The impressive Kane, who was the visitors’ best player, is. He would provide stiff competition for Rooney and Van Gaal is an admirer – but prising him from White Hart Lane may be impossible.

Tottenham faded after a bright start and became a threat again towards the end. This meant the sight of United’s players having to hang on to their slender lead in front of their own crowd. Given the manager’s £230m investment since taking over, this should not be the case. With David de Gea dropped because of his distraction at Real Madrid’s interest, Romero impressed. The Argentina No1 made a fine debut and his save from Eriksen’s late shot ensured United secured three points.

All of the Van Gaal new boys were on show but Matteo Darmian was the pick of them, as he offered an accomplished display at right-back. Morgan Schneiderlin, who lined up alongside Michael Carrick, was caught in possession and misplaced passes. Bastian Schweinsteiger, who replaced Michael Carrick, was booked and did not appear in optimum shape. Memphis Depay was again selected in the No10 role behind Rooney.

How did Van Gaal think the young Dutchman fared? “It is a new position for him and he has to adapt because he is a goalscoring type. We have to wait and see if he can fulfil the demands of this position but [he’s playing there] because Ashley Young is playing very good on the left side,” said the manager.

“Therefore that is the circumstances but it can change during the season. He can play in this position.”

The big hope for manager and fans alike is that United’s calibre of performance can also be transformed.