New Manchester United goalkeeper Andre Onana had a furious rant at Harry Maguire after the defender made a slack pass to Christian Eriksen that gave Dortmund a chance.
Onana denied Sebastian Haller then raced from his goal to berate Maguire.
United were beaten 3-2 by Dortmund in Las Vegas.
The 27-year-old Cameroonian has shown he will bring more to the team than his ball-playing ability.