Louis van Gaal may need to act quickly to reinforce his squad before the opening fixture and with very little progress in his chase for Arturo Vidal, he may revert back to his original, more realistic targets, Daily Star reports.
He is now believed to be targeting the likes of Dutch trio Daley Blind, Ron Vlaar, and Kevin Strootman, all of whom have been previously linked with the club.
Blind was very impressive at the World Cup for his national team with Van Gaal keen to add his versatility to the Manchester United squad as the 24-year-old can play both in defence and in midfield.
Aston Villa captain Vlaar was another top performer in Brazil as the 62-year-old manager plans to add some extra cover to his three-man back line.
With only Jonny Evans, Phil Jones, and Chris Smalling being the only three experiences centre-backs, the Villa man is considered a highly possible target.
Lastly, Strootman, who Roma currently value at £80million is another player who is linked with the Red Devils, but due to his lengthy injury, the manager is likely to negotiate a move in the January window instead.