Former England captain Lawrence Dallaglio will lead a World XV side taking on a Saracens XV in a match in aid of Richard Hill's Benefit Year.
Other stars to take part at Vicarage Road on Sunday include Carlos Spencer, Justin Marshall, Matt Burke, Joe Roff and Owen Finegan.
Hill will manage a Saracens XV which features former players Dan Luger and Tony Diprose.
Diprose and Kyran Bracken are playing their final games before retirement.
The World XV side will be coached by Bob Dwyer, Mike Ruddock and Craig Dowd.
The game will also help to raise money for the Wooden Spoon Society, Anthony Nolan Trust and the Saracens Foundation.
World XV: Matt Burke; Bruce Reihana, Joe Roff, Fraser Waters, Iain Balshaw; Carlos Spencer, Mark Robinson; David Hewett, Mark Regan, Peter Bracken, Simon Shaw, Tom Palmer, Owen Finegan, Sam Harding, Lawrence Dallaglio (c).
Replacements: Raphael Ibanez, Christian Califano, Daniel Leo, Xavier Rush, Justin Marshall, De Wet Barry, Cedric Desbrosse.
Saracens XV: Thomas Castaignede; Dan Luger, Ben Johnston, Kevin Sorrell, Tevita Vaikona; Glen Jackson, Moses Rauluni; David Flatman, Matt Cairns, Ben Broster, Simon Raiwalui, Tom Ryder, Kris Chesney, Ben Russell, Tony Diprose.
Replacements: Nick Lloyd, Shane Byrne, Craig Yandell, David Seymour, Kyran Bracken, Pat Howard, Adam Powell.