Glen Jackson is set to make history this weekend when he becomes the first New Zealander to both play and referee 100 first-class games.
Jackson will achieve the milestone when he referees the Test between Argentina and South Africa in Buenos Aires on Saturday.
He played 60 Super Rugby games for the Chiefs, 51 games for Bay of Plenty, 49 games for Waikato and 130 times for Saracens before retiring in 2010 to take up refereeing.
Jackson admits that preparing for a game as a referee is very different to what he was used to as a player.
"In rugby you could prepare yourself for an opposition, and how to out-perform the opposition and what to do to try and get a win," he told allblacks.com.
"As a referee you have to do exactly what is in front of you. You can prepare all you like but it's what is served up in front of you [that you have to deal with]. That and being able to think quickly on your feet.
"That has been the biggest change in terms of how you prepare during the week and what preparation you can actually do. It's about being ready for everything I suppose."
Jackson, who initially thought about refereeing before he left New Zealand to play for Saracens in 2004 but only gave the idea serious consideration during his last season with the Premiership side.
"It was a case of coaching, getting a real job or refereeing," added the 39-year-old who – along with countryman Chris Pollock and South Africans Craig Joubert and Jaco Peyper – will be one of four southern hemisphere-based referees in charge of matches at the World Cup.
He admits that he is surprised at how fast he has gone through the refereeing ranks.
"It's been a hell of a lot of hard work but at times pretty rewarding as well," said Jackson.
"I never expected to start refereeing four or five years ago and go to a World Cup so I'm pretty stoked to be doing that."