Images of Patrick van Aanholt smoking a shisha pipe have emerged only a month before he was withdrawn on medical advice.
The Dutch defender was questionably left out of the black Cats starting line-up just 15 minutes prior to the weekend's clash with Tottenham Hotspur at White Hart Lane.
It was understood that heart issues prompted doctors to withdraw van Aanholt from the match, with Jason Denayer replacing him in the starting XI.
While the 26-year-old has played down suggestions he has health issues, the club will be infuriated that The Sun has got hold of pictures of him smoking a shisha with a close friend in Newcastle in the lead-up to the season opener against Manchester City in mid-August.
A source told The Sun: “Being a lifelong Sunderland supporter, it was a poor sight to see.
“Having just survived relegation last season, Patrick didn't seem to be showing fans he was serious about this season.
“It looked like he was prioritising his lavish lifestyle over gearing up for a big match against City."
EXCLUSIVE: Patrick van Aanholt spotted smoking shisha weeks before health concerns raised https://t.co/3eimH9J683pic.twitter.com/ESljnPSsQZ
— Sun Sport (@SunSport) September 22, 2016