According to Erik ten Hag, the manager of Manchester United, players require discipline both on and off the field.
His remarks coincide with the week that England striker Marcus Rashford was forced to own up to his mistakes following reports that he was sighted twice in Belfast nightclubs.
After traveling from Northern Ireland to Manchester on Friday for United's training, Rashford suddenly felt sick.
He was not involved in the FA Cup victory over Newport on Sunday.
When Ten Hag met the media before his team's Premier League trip to Wolves on Thursday, he steadfastly refused to discuss Rashford's circumstances.
When questioned whether he was giving his players the proper discipline, he responded, "It has nothing to do with me, but in football, you need discipline, both on and off the field."
"There is a line between, every player, every professional knows this, what is required."
The Sun published allegations regarding Rashford's behavior on his nights out that did not bode well for the 26-year-old.
Ten Hag has chastised Rashford three times in the last thirteen months as a result of off-field problems.
He was benched for the season finale against the Wolves because he slept in too late and skipped a team meeting. Then, hours after United's humiliating 3-0 home loss to Manchester City in October, he apologized to Ten Hag for attending a scheduled birthday celebration.
Ten Hag disputed that Rashford's constant wrongdoings were an act of disrespect towards him.
"It's nothing to do with that but as I said, let's focus on the game, let's move on," he replied. "We must concentrate on winning football matches.
"The other problems are internal; he has taken responsibility. closed the matter."
Ten Hag is eager for Rashford to maintain his recent form, which has seen him score two goals and provide an assist in his previous two Premier League games. Rashford will go to Wolves with the United team.