Jose Mourinho's side played their first game of the summer, drawing 1-1 with Mexico's Club America in Phoenix overnight.
Star midfielder Paul Pogba also struggled to influence games consistently and Mourinho's defensive-minded tactics were often called into question.
Manchester United have announced forward Alexis Sanchez will be joining up with the squad for their pre-season tour of the United States. Deprived of all of the players that appeared at the World Cup in Russian Federation, a visa issue meant that Alexis Sanchez has also been unable to fly out for the first week of the tour.
Mourinho said: "The line-up has the most possible I would say men, because the objective is to prepare them the best we can for the start of the season as we don't have many more players than this one".
Paul Pogba and Romelu Lukaku were among seven United players to make it to the final weekend of the tournament in Russian Federation and are now set to miss the start of the Premier League season.More news: PM Modi slams previous UPA regime for shoddy work on electrification
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The World Cup has forced Mourinho to take a young squad to the United States and presented the likes of Ethan Hamilton, Mason Greenwood and Josh Bohui with a fantastic opportunity to impress.
"Yeah he was good, he came with the intention to show [his quality] in a moment where we have no strikers on the pitch".
"The action for the cross which led to the goal was lovely".
Grant was replaced by Joel Pereira at half-time and the 22-year-old - who is set to leave on loan for the 2018-19 season - prevented America from taking the lead eight minutes into the second period when he thwarted Martinez. "He was enthusiastic and he had the confidence to play".
"Of course physically he has his limitations, and when he has one more touch and allows the body contact, he loses for everyone, but when he makes the ball move and when he attacks people one against one, he has qualities".