Dramatic pictures appear to show Manchester City bad boy Mario Balotelli in a physical bust-up with Roberto Mancini, his manager.
The images show the pair tussling and and grabbing each other before they were restrained by colleagues.
Sir Alex Ferguson says it would never be possible to gain access to Manchester United's training sessions.
Manchester City manager Roberto Mancini has played down his latest confrontation with controversial striker Mario Balotelli.
Mario Balotelli's Manchester City future is in doubt after he was photographed in a training-ground bust-up with manager Roberto Mancini.