Sunderland reportedly had no idea that Adam Johnson intended to plead guilty to charges of grooming and sexual activity with a child at Bradford Crown Court yesterday afternoon.
Winger Johnson, who was arrested for the offences in March 2015, had previously denied all the charges that were brought against him.
However, during yesterday's hearing the England international, 28, admitted to grooming a 15-year-old schoolgirl and conceded that he had kissed and touched her.
According to the Daily Mail, the Black Cats were shocked to learn that their player had altered his plea.
As a result, the report adds that manager Sam Allardyce will now have no option but to leave him out of the squad for this weekend's clash against Manchester United, despite having previously stated that Johnson would play throughout his trial.
Johnson has also denied two further counts of sexual activity with a child under 16, both involving penetration. The maximum sentence for those offences is 14 years in prison.
