Jose Mourinho has admitted that he "did not learn anything" from Manchester United's pre-season tour of the United States.
The Red Devils concluded their two-week stay in the early hours of Wednesday morning with a confidence-boosting 2-1 win over European champions Real Madrid.
United have endured a pretty tumultuous trip on the whole, however, with three draws and a defeat in their other Stateside friendlies, on top of numerous complaints from Mourinho.
"I know the kids are very young and need time to grow up, I know my players gave everything and in the last 15 minutes, we are dead and they bring on Toni Kroos and [Marco] Asensio and Isco and I thought we wouldn't resist but we did. That's the spirit we need, because our first two or three weeks in the Premier League are going to be really hard for us... we didn't prepare for that.
"People like Herrera, [Eric] Bailly, [Matteo] Darmian, Mata, all these guys, were phenomenal during the whole pre-season, playing almost every minute of every game. The game today - if we win 2-1, we lose 2-1 or draw 2-2 - it doesn't change anything but of course I know the players and I know I can count on them.
"I know that these guys are amazing professionals and I know that they give everything for the club, for the prestige of the club. The guys were absolutely phenomenal. My players were amazing in their effort but we have more effort in front of us."
United face Bayern Munich in Germany on Sunday, before turning attention to their Premier League opener against Leicester City five days later.