Arturo Vidal
The signing of Arturo Vidal may prove beyond Manchester United this summer. Reuters

Louis van Gaal is not a man lacking in confidence or ambition. Happy to boast his own arrogance, the veteran Dutch coach has won league titles in three countries with each of his four clubs -- European giants Ajax, Barcelona and Bayern Munich, as well as previously success-starved AZ Alkmaar. As he arrived at Manchester United’s training complex for his first official day’s work in his new job on Wednesday, among his first words to his squad were surely that the Premier League title is the primary target in his first season in charge.

The reign of his predecessor, David Moyes, was a disaster from start to finish, beginning with hapless dealings in the transfer market. Despite negotiating a successful World Cup campaign with the Netherlands, Van Gaal has proved decisive in green-lightning deals for Ander Herrera and Luke Shaw and extending the contract of Antonio Valencia. Now that the 62-year-old is fully focused on his new role, further decisions over the makeup of his squad are likely to come swiftly. A tour of the United States presents Van Gaal with the intense environment with which to examine what he has and what he still needs. Here are the positions he is likely to discover are still in need of strengthening.

Center Back
Nemanja Vidic and Rio Ferdinand may have been past their best but the duo’s departure leaves a significant void at the heart of Manchester United’s defense. It is a gap that Johnny Evans, Phil Jones nor Chris Smalling has yet shown that they can be relied upon to fill. Indeed, Smalling may yet be on the move before the transfer window shuts. Securing an experienced, high quality option is believed to be a priority, with German World Cup winner Mats Hummels a leading target. Yet it remains an extremely difficult prospect to prize him away from Borussia Dortmund. A member of Van Gaal’s Netherlands squad, Stefan de Vrij, has been strongly linked, but now looks set for a move to Lazio. Instead, a likely arrival is Arsenal’s Thomas Vermaelen, if the two Premier League rivals can reach a compromise. The fact that Vermalen can play left-back and cover for Luke Shaw, should Patrice Evra depart, adds to his appeal.

Commanding Midfielder
It’s almost redundant to include the need for a dynamic midfield presence, so long has it been apparent. Moyes’ purchase of Marouane Fellaini failed to address the gaping void in central midfield and the purchase of Herrera, more of a creator, arguably doesn’t either. The arrival of Arturo Vidal is undoubtedly the dream scenario. The Juventus star would almost solve all of United’s midfield problems over the past five years in one fell swoop. The Chilean is currently the best all-round midfielder in the world -- able to tackle, pass and get forward to score. Despite the shock departure of manager Antonio Conte this week, Juventus insist Vidal is not for sale. United may have to lower their ambitions.

Winger
Manchester United’s pace and creativity on the wings was for so long what defined them under Sir Alex Ferguson. But since the departure of Cristiano Ronaldo United’s wingers have been far less spectacular. Valencia’s new contract has merit if the Ecuadorean can regain his previous form, but the futures of Nani, Ashley Young and Wilfried Zaha should be in serious doubt. With Van Gaal preferring a 4-3-3, it could well be that Juan Mata or even Wayne Rooney, Shinji Kagawa and Danny Welbeck are seen as wide options, but a top class natural winger would provide a major boost. Ángel di María has been strongly linked and the Real Madrid man, who has also played in a midfield three, would be a superb signing. Paris Saint-Germain’s interest may scupper a move, however. Despite reports, there appears little chance of Arjen Robben, star of Van Gaal’s Dutch side at the World Cup, leaving Bayern Munich for Old Trafford.

Striker
Injury problems returned for Robin van Persie last season and, while some of that may have been down to Moyes’ training methods, it would be dangerous to be overly reliant on the 30-year-old. While Rooney can also lead the line, the declining production and uncertain future of Javier Hernández means that another quality striking option should be desired. Edinson Cavani has been linked and has reportedly instructed his agent to look into a transfer to the Premier League this week. But having cost Paris Saint-Germain over £50 million just a year ago and after a disappointing past few months, a deal for the 27-year-old may not be the most prudent piece of business.