Manchester United manager Erik ten Hag canceled a planned rest day for his players as a consequence of their 4-0 defeat at Brentford.
Ten Hag's squad had been due to have Sunday off following Saturday's Premier League trip to west London.
But the new manager clearly thought that there was plenty to work on after seeing his team fall to last place in the EPL table.
According to BBC Sport, Ten Hag was in his office early on Sunday morning to analyze United's first ever loss to Brentford.
The Dutchman later addressed his squad before putting them through their paces in an extra training session.
Ten Hag publicly described United's performance as "rubbish" in his post-game interview on Saturday.
Speaking to beIN SPORTS, he said: "It's rubbish and it's poor. We need higher standards than that, that's clear.
"We have to deliver and we didn't. We have to change, that's quite clear.
"In 35 minutes you concede four goals. It is not possible. The team has to take the responsibility. I feel really sorry for the fans. We let them down."
United's first two goals had been partly caused by errors from David de Gea.
The goalkeeper volunteered to speak to Sky Sports after the match.
De Gea said: "I cost three points to my team today, to be honest.
"It was a poor performance from myself. After the first mistake and the second, it was very tough for the team to get playing. It was a horrible day."