David Moyes wants his Sunderland players to set a better example to younger fans after defender Patrick van Aanholt was photographed apparently smoking a shisha pipe.
The 26-year-old, who was withdrawn from the defeat to Spurs last weekend because of a heart scare, was pictured in the national press.
The pictures dated back to the off-season but Moyes says he was "not impressed" and has spoken with the Dutch international.
Shisha smoking, which is not illegal, is a way of smoking tobacco, sometimes mixed with fruit or sugar, through a bowl and hose or tube.
Speaking at his pre-match press conference, Moyes said: "We should be talking about football and signs of improvement after the QPR win.
"But we are talking about Pat.
"I think he has been wrong. It is not good that young supporters, people who look up to him have seen him in this environment, this situation.
"I do have to say it was in his off time.
"It wasn't during the season. But I want my players fit and able to run more than we are at the moment and harder than we are and I want everybody in the best condition.
"I'm not too sure doing what he has done, does that."
The British Heart Foundation warns about the potential health dangers of smoking a shisha pipe on its website.
It reads: "The average shisha-smoking session lasts an hour and research has shown that in this time you can inhale the same amount of smoke as from more than 100 cigarettes."
The Sunderland boss added: "I'm not impressed by what he has done. It is not the way I want my players to behave.
"I certainly want them in the best physical condition to win games.
"That is the biggest thing."
Van Aanholt will be in the squad for the clash with Crystal Palace at the Stadium of Light after undergoing further heart tests and coming through Wednesday night's 2-1 EFL Cup third round victory at QPR unscathed.
Sunderland have moved to draw a line under the saga at Spurs, which saw van Aanholt withdrawn from the team 40 minutes before kick-off.
He had been named on the team sheet and had completed a warm-up before fellow defender Jason Denayer was filmed telling the left-back he was replacing him in the side.
There was confusion after it was originally stated van Aanholt had been withdrawn after advice from cardiologists, who sit on the FA Consensus Panel.
But the FA then released a statement distancing themselves from their involvement in the situation.
The cardiologist involved in van Aanholt's case does sit on the panel but was working independently from the FA in this case.
"The timing of the decision was very difficult for us," said Moyes.
"Ultimately the decision was taken for the right reason.
"He did well against QPR. It was a late call that he would play.
"Mentally, he showed no affects. It was a pretty good game for him to get back into it and get on with it."