Mick McCarthy described Robbie Keane as a "street" player who loved the game after the Republic of Ireland captain announced his international retirement.
Keane was handed his senior debut by McCarthy against the Czech Republic in March 1998, wearing the shirt for the first time as a 17-year-old.
He has gone on to win 145 caps and score 67 goals - a record goal tally - and will bow out after next week's friendly with Oman.
"He was a joy to manage," McCarthy told Sky Sports News.
"He is a terrific footballer and at the age of 18 he used to light up the place in training.
"Whether we played home or away, he still played with the same joy.
"He was like a street footballer that just loved playing.
"He wasn't just a street footballer that juggled the ball. He had such a quick brain and he was terrific."
Keane formed a formidable partnership with Niall Quinn for part of his Republic career and it was his goalscoring record of 21 he surpassed.
"This was kind of doing the rounds that he was going to go out with a bang and say goodbye," Quinn told Sky Sports.
"When you think of everything he has achieved and done in the green jersey, it has been Roy of the Rovers stuff.
"It's impossible as someone like me, who was around trying to break the record like myself... I was fortunate to sneak a goal ahead of the others and then this fella came along and laughed at us and blew it into the history books."