The Portuguese manager has not been happy of late, after he was forced to take a number of young players on his preseason tour because 12 of his star men are on holday having played in the World Cup, such as Paul Pogba and Romelu Lukaku.
"I don't have the majority of the players that are going to be in the squad on 9 August when the market [transfer window] closes and we can make it official for the season. So of course I'm not happy, to have just a few players," he said.
With this disappointment, which has seen his team draw their first two preseason clashes in the USA, the former Chelsea and Real Madrid boss has made his discontent known about the strength of his squad going in to the new season.
Despite this, Mourinho is hopeful that he can make two more sigings, according to 'ESPN', before the transfer window shuts on 9th August.
In a press conference, he would not answer a question on whether the 'Red Devils' were capable of lifting the Premier League trophy this season for the first time in 6 years, giving no indication as to why he would not give an answer.
This coming season will be vital for the Old Trafford club, with the failure to win a major trophy potentially spelling the end for their manager.