Newcastle defender Steven Taylor was recovering in hospital on Tuesday amid reports of a training ground bust-up with striker Andy Carroll.
The 24-year-old was said to be in a stable condition on the orthopaedic trauma ward at Newcastle General Hospital, but the Magpies were not commenting on reports that Taylor suffered a broken jaw in an incident on Sunday and will not play again this season.
It remains to be seen whether Carroll, 21, will play in Tuesday night's Coca-Cola Championship trip to Doncaster.
It is understand an internal investigation is underway as manager Chris Hughton, owner Mike Ashley and managing director Derek Llambias attempt to discover exactly what happened.
Newcastle have attracted the wrong kind of headlines in recent years, most notably over the astonishing on-field spat between colleagues Kieron Dyer and Lee Bowyer, and Joey Barton's spell behind bars.
However, a new-found stability off the pitch in recent months and positive results on it had provided a welcome respite with the prospect of a swift promotion back to the top flight the main focus of attention.
Ashley and Llambias will be furious that a self-inflicted wound is threatening to wreck the growing feelgood factor.
Taylor was nearing the final stages of his rehabilitation from the knee injury which has sidelined him since January, and had hoped to play a part in the club's final few games of what has to date been a successful season.
Carroll is one of the club's emerging stars and is currently top scorer after collecting his 15th goal of the season in Saturday's 2-2 draw at Bristol City.
However, he is facing a Crown Court appearance next month after being charged with assault following an alleged incident at a city nightspot in December last year.