Gregan is the Barbarians' latest high-profile addition for the London Olympic Centenary Match at Wembley on December 3.

The gifted scrum-half, who won 117 caps for Australia and now plays club rugby in Japan, joins the likes of Richie McCaw, Bryan Habana, Joe Rokocoko and Jerry Collins in a star-studded squad.

The Barbarians have also announced that current Saracens boss Eddie Jones - Gregan's former Wallabies coach - will assist Jake White in preparing the side.

It means White and Jones will be reunited after they masterminded South Africa's World Cup success last year.

White said: "The Barbarians are putting together a powerful squad of all the talents for this very special match.

"I have been impressed by the positive response from so many players worldwide, and to have Eddie to assist me in the build-up is definitely an added bonus."