Ireland number 8 Jamie Heaslip, Australia's Matt Giteau, Tom Croft of England and South African duo Francois Steyn and Fourie du Preez compete against two international captains in Ireland's Grand Slam-winning skipper Brian O'Driscoll and Richie McCaw of New Zealand to win the most prestigious individual award in rugby union.
IRB Chairman Bernard Lapasset said: "The IRB Player of the Year award is the ultimate accolade for a player and takes into account performances in all internationals played during the year, including the RBS 6 Nations, British & Irish Lions Test series, Tri Nations and the June and November Tests.
"The list of past winners includes the iconic names of the decade - Jonny Wilkinson, Schalk Burger, Richie McCaw, Fabien Galthié, Dan Carter, Bryan Habana and Keith Wood - they have all been worthy recipients of the award.
"Richie McCaw could become the first player to receive the accolade twice."
The nominees were selected by the IRB Awards independent panel of judges, comprising former internationals with over 500 Test caps between them.
Will Greenwood, Gavin Hastings, Raphaël Ibanez, Francois Pienaar, Agustin Pichot, Scott Quinnell, Tana Umaga, Paul Wallace and convenor John Eales watched over 60 hours of action from 46 matches, awarding points to the three players they thought stood out in each match.
"Now that the shortlist has been selected, the panel will reconvene at the completion of the November Tests when the IRB Player of the Year will be selected.
"The announcement will be made at the conclusion of the final weekend of matches," added Lapasset.
The Player of the Year award is the sixth of the 13 coveted IRB Awards in association with Emirates Airline to be presented in 2009.
In May, England captain Ollie Phillips was named IRB Sevens Player of the Year, while New Zealand captain Aaron Cruden was named IRB Junior Player of the Year in June.
Australia's Debby Hodgkinson was named IRB Women's Personality of the Year in August and L'Aquila Rugby Club received the Spirit of Rugby Award in September.
This month, Francis Palmade received the IRB Referee Award for Distinguished Service.
In a new format for the IRB Awards, the winners have been named throughout the year, culminating in the announcement of the prestigious IRB Player, Coach and Team of the Year later this month.
2001 - Keith Wood
2002 - Fabien Galthié
2003 - Jonny Wilkinson
2004 - Schalk Burger
2005 - Dan Carter
2006 - Richie McCaw
2007 - Bryan Habanna
2008 - Shane Williams