Martin O'Neill has again championed Roy Keane's candidacy for the Celtic job.
Former Manchester United captain Keane, 49, has been heavily linked with replacing Neil Lennon at Celtic Park following his departure last month.
Keane was O'Neill's assistant on two occasions, between 2013 and 2018 for the Republic of Ireland before the pair joined forces again as No 1 and No 2 at Nottingham Forest in 2019.
"He's got the personality for a start," O'Neill - who was also a highly successful manager at Celtic - told BBC Scotland Sportsound.
"He was a massive player, an iconic figure in the game, one of the best midfield players in the modern day Premier League. He led and cajoled Manchester United on for almost a decade.
"He's very strong-willed, and I know people then start to feel strong-willed people do not necessarily change or adapt. He has certainly got the capacity to do that - to motivate players, absolutely.
"I worked with him at close hand. Sometimes in this game you get a reputation and that supersedes anything that you're trying to do. Roy Keane has learned a great deal in the intervening years.
"He was my assistant at Ireland and I know that's a totally different job, but has Roy Keane got the personality to manage at the very top? Absolutely."
