[Diego Simeone](/topic/diego-simeone)’s side, however, were forced to return to their hotel after the session and shower there because there was no hot water in the dressing rooms at the Emirates.
The issue is understood to have impacted both the home and away dressing rooms at the ground.
Atletico Madrid staff alerted Arsenal to the problem at 6.45pm on Monday, while their players were training.
The session had been due to finish at 7.30pm, but it was completed 15 minutes ahead of schedule.
The issue with the hot water was not resolved until 7.25pm, by which point Atletico had decided to go back to their hotel to shower there.
Arsenal apologised to staff from the Spanish club for the inconvenience caused.
UEFA regulations on infrastructure state that stadiums must be equipped with showers that have hot water, however it does not specify whether these rules apply to training sessions or just match days.
UEFA have been contacted by **Standard Sport** for comment.