Louis van Gaal has admitted to his surprise at Manchester United's "unbelievable" following from supporters around the world.
Van Gaal's United played in front of 109,318 fans at Michigan Stadium last summer in the United States when they beat Real Madrid 3-1 in a friendly.
The Premier League giants announced in April they will to face Barcelona and Paris Saint-Germain in a four-game tour of the United States in July.
Reflecting on last summer's preseason tour, Van Gaal said in the Daily Mail: "That was unbelievable. It was the first few days of my managership in Manchester and the way of the enthusiasm of our fans and the amount of numbers was unbelievable.
"We have played four or five games there [in the U.S.] and there were 300,000 fans in two weeks.
"Of course [in Michigan] they were also watching Real Madrid but most of them were in red shirts. It's amazing."
The Dutchman added: "When I drive to the Aon training complex I think there are 100 people who want me to sign a shirt or a photograph and most of these are from Asia,' he explained.
"It is unbelievable how popular Manchester United is."