Roy Keane has questioned Gary Neville for continuing to call Sir Alex Ferguson 'boss', amid the former Manchester United captain's feud with the legendary manager.
Keane and Ferguson have not seen eye-to-eye for many years, following the Irishman's bitter exit from Old Trafford in 2005.
The ex-Man United skipper has previously hit out at the 'cold' nature of his exit from the club, with his relationship with Ferguson yet to be repaired nearly two decades on.
Ferguson remains revered by the majority of his former players, having led the club to 38 trophies and 13 league titles during 26-and-a-half-years at Old Trafford.
Keane speaking on the Stick to Football podcast, brought to you by Sky Bet, was asked to rank the top five Premier League managers following Jurgen Klopp's departure from Liverpool.
Roy Keane quizzed Gary Neville on why he continues to call Sir Alex Ferguson 'boss'
Keane has had a long-standing feud with the former Man United boss over his departure
Ferguson has continued to be revered for former Man United stars including Neville, right
After placing Ferguson second in his all-time ranking, the 52-year-old questioned Neville, who succeeded Keane as Man United club captain in 2005, about why he still refers to Ferguson as 'boss' long after his retirement.
'Why do you call him [Sir Alex Ferguson] boss?,' Keane asked.
'He was your manager of a football club, his contract was with the club and your contract was with the club, why do you call someone boss? Do you call anyone else boss, besides your wife?'
Neville, who only played under Ferguson during his club career, responded: 'I still call the school teacher who I was brought through Mr. Wright. You've been used to calling someone that for twenty-five years.'
'I don't get it. Not just you, everyone,' Keane replied.
Neville added 'I would never call him Sir Alex, or Alex. For twenty-five years I called him boss.'
'He's not your boss now, is he? He's another human being, why are you calling him boss?,' Keane said.
Keane, however, acknowledged the success he had at Man United under Ferguson had been 'absolutely amazing', despite their frosty relationship since.
Neville explained that he was used to calling Ferguson 'boss' over a 25 year period at the club
Keane admitted his time under Ferguson was 'absolutely amazing' before leaving the club in 2005, leading to Neville succeeding him as Man United's club captain
Keane had previously spoken of how Ferguson and David Gill had sat him down and had prepared a statement for him to that announced he was being let go.
The 52-year-old had controversially walked out of Old Trafford back in November 2005 after appearing in an interview on MUTV where he criticised his team-mates' performances following a 4-1 defeat by Middlesbrough - a game in which Keane did not play in.
The incident infuriated his manager, Ferguson, with the United boss opting to fine the midfielder £5,000 before sitting him down in a meeting with chief executive Gill to tell their former captain that they would be severing his contract.
Keane scored 51 goals and provided 38 assists in 478 appearances across all competitions for Man United between 1993 and 2006.
He won seven Premier League titles at the club, as well as four FA Cups and one Champions League title, playing a key role in the Red Devils' historic treble winning campaign in 1999.
After his departure from United, he went on to play for Celtic for half a season in 2006 but his career was cut short after rupturing his anterior cruciate ligament and was told by medical professionals to retire.
Roy Keane was speaking on the Stick to Football podcast, brought to you by Sky Bet