Louis van Gaal gave his Manchester United players the first glimpse of his temper after they conceded two late goals against Roma .
United were leading 3-0 in Denver, thanks to two goals from Wayne Rooney and one from Juan Mata, but endured an anxious finale.
Van Gaal was unhappy the game kicked off at 2pm local time, for TV purposes, with the temperature at the Sport Authority Field hitting 31C.
The United boss was not impressed with the performance of his team, despite a wonder strike from Rooney and a fine assist from him for Mata's goal.
But the Dutchman was equally unhappy with the tournament organisers, who made sure the game was played at the hottest part of the day to maximise the potential TV audience.
Van Gaal said: “I think we didn't play a good match.
“I don’t know whether it was because of the height of the stadium, the air, but all of my passers failed today. It wasn’t normal.
“It was the height and the air, the ball was bobbling all the time, but we scored remarkable, fantastic goals and were able to keep the ball in possession in the second-half.
“When you are 3-0 ahead, you just have to keep the ball, as the opponent has to run and run.
“It is very difficult, with this hot weather, to do that. We forgot to do that and we allowed Roma back into the game.
“I'm pleased we have won, but it was not good. We are not used to this hot weather and I have said also that, when the World Cup was here in 1994 and games were played at noon, it was not very nice.
“America has a top sport climate, but you have to play football at the right time.
”You had 55,000 people watching us but we could have performed much better. It was the height and the heat, though.”
Van Gaal also had a pop at United keeper Ben Amos, who was beaten by a long-range strike by Miralem Pjanic, from inside his own half.
Amos was caught out by the audacious strike and Van Gaal clearly felt the young keeper, who came on at half-time, was to blame.
“I am nearly 63 years old and I run when the ball is flying four seconds from fifty metres,” said van Gaal. “What do you think?”
Roma grabbed a second goal with a Francesco Totti penalty two minutes from time, but the Red Devils held on for the win.
Van Gaal did reserve praise for Rooney, whose 45-minute outing earned him the man-of-the-match award.
“We don’t discuss one player, we discuss the team,” said Van Gaal.
“The team is performing, but his pass to Mata was unbelievable - in spite of the height and the heat!
“But he did it with his brain and Mata was running with his brain.”
Wilfried Zaha is the only one of the 26 United players on the tour yet to play, but Van Gaal said he was not freezing him out.
“There is no Manchester United player who is fit,” said Van Gaal.
“Maybe the boys who trained before the World Cup players started on July 7.
“Maybe they are more fit, but also not fit. The World Cup players have only had four days' training.
“You cannot say they are fit, but I have a lot of strikers and I have already said we have no balance in there.
“Maybe the next time I can use Zaha, but he is working good and doing all that I demand.