Mario Balotelli's volatile relationship with Manchester City manager Roberto Mancini appeared to escalate Thursday when the two men were photographed in a heated altercation during training.
Mancini shouted at the Italy striker and grabbed his training bib before the pair were separated.
The incident occurred after a tackle by Balotelli on a teammate, according to online news reports accompanying the photographs.
The training session was closed to the media but City's training pitches are viewable from public walkways. Exactly two years ago, a brawl between Kolo Toure and Emmanuel Adebayor was photographed on the same pitches.
Thursday's altercation is the latest chapter in Balotelli's turbulent City career and overshadowed the club's preparations for an FA Cup third-round match against Watford on Saturday.
Mancini has become increasingly frustrated with Balotelli as the 22-year-old player's form has dipped this season.
But Mancini has insisted that his compatriot will not be sold in the January transfer window, saying earlier this week that the club's Abu Dhabi owner is a fan of the striker despite a series of disciplinary violations that led to Balotelli being fined two weeks' wages.
"Sheikh Mansour likes Balotelli because he recognizes the talent and he exports the name of City over the world,'' Mancini told Italian newspaper La Gazzetta dello Sport. "We need to realize Mario was signed as a major investment and this is not a club that throws its capital through the window. I think Mario will stay but the future depends mostly on him.''
Balotelli joined City from Inter Milan in 2010, but has rarely been out of the headlines, creating continuous uncertainty about his future.
He made light of his troubles in 2011 by unveiling a T-shirt with the slogan "Why Always Me?'' during City's 6-1 rout of Manchester United in a Premier League match. That came after news emerged that a fire had broken out at his house when fireworks were let off in his bathroom.
Balotelli escaped punishment earlier in 2011 after throwing a dart at a City youth-team player. No one was hurt in the incident.
Brawling with the manager, though, could be a step too far for Balotelli. City wasn't commenting on the latest incident on Thursday, leaving it to Mancini to respond at his pre-match news conference the following day.