Cardiff City owner Vincent Tan has told manager Malky Mackay to resign or face being sacked, according to the BBC.
Tan sent a letter to Mackay on Monday, listing a number of grievances he holds with the Scot.
Tan is understood to have criticized Mackay in a number of areas, including signings, transfer budget, style of play and results on the pitch.
The Malaysian businessman is also understood to have questioned Mackay’s record as a manager.
Mackay had previously stated he will not resign from his position, but it now seems unlikely he will remain in the Cardiff hot seat for much longer.
A Cardiff spokesman told BBC Sport: “The club is not party to any letter sent from one person to another.”
The letter from Tan came on the same day he had issued a statement criticizing Mackay through Cardiff chief executive Simon Lim.
One of Tan’s issues surrounds the supposed over spending in the summer, after Cardiff broke their transfer record three times to bring in striker Andreas Cornelius for £7.5million, defender Steven Caulker for £8million, and midfielder Gary Medel for £11million.
Tan was said to be ‘extremely upset’ following comments from Mackay that stated he hoped to bring in three new players in January.
The owner claims the club overspent by £15million in the summer, claiming £50million was spent rather than the agreed £35million.
Mackay has been in charge of Cardiff since June 2011, and led the club to the Premier League last season via winning the Championship.
His position at the club has been under scrutiny since October, when head of recruitment Ian Moody was removed from his position by Tan.