Erik ten Hag admits hard work ahead after Man Utd's Rosenborg loss

The majority of the first-team squad were not involved in Trondheim, and Jadon Sancho, who has returned to training after resolving his differences with Ten Hag, was also not part of the travelling group which was mostly made up of youth players.

Marcus Rashford, Mason Mount, Casemiro and Aaron Wan-Bissaka, though, were all in the starting line-up at the Lerkendal Stadion, along with veteran defender Jonny Evans.

With Rosenborg already in league action, the hosts were far sharper than United, and Czech goalkeeper Radek Vitek was forced to make a string of saves while winger Marius Broholm twice struck the United woodwork.

Ten Hag made the expected sweeping changes for the second half, replacing all 10 outfield players with academy products.

However, it was Rosenborg — having earlier again hit a post — who eventually made the breakthrough when Noah Holm tucked in a late winner during stoppage time.

United are set to face Rangers at Murrayfield on Saturday before then heading out to the United States to step up preparations for the new campaign ahead of the FA Community Shield against rivals Manchester City at Wembley on August 10.

Ten Hag expects a much-improved display for their next pre-season run-out.

"The result is not secondary. Of course, we play pre-season, but at Man United the standard is you win games and definitely don't lose games," the Dutchman said.

"So if you can't win, don't lose the game, like we did in the last second of the game, but of course, the performance is more important and the performance was below standards."

Ten Hag, who recently signed a contract extension until 2026, added: "We can talk (about) everything that is bad, but I am not that guy.

"I have seen and this is not the standard for top football. Top football, you have to achieve much higher standards, starts with any individual, make sure you are fit.

"I know we can't be match-fit in this moment, I know you need these games. The opponent is (playing already) in the league, so they have a much higher fitness level — but we are Man United and should perform better."