South Africa's Eben Etzebeth, Handre Pollard and Tendai Mtawarira have joined Australian scrum-half Will Genia in accepting invitations to appear for the Barbarians in December.
The invitational side face Argentina at Twickenham on Dec. 1 in their first match since defeating England 65-45 in May. The players are the first four members of the Baa-Baas' Killik Cup squad to be announced and have almost 300 international caps between them.
Pollard and Etzebeth will pull on the iconic black and white jersey for the first time while Mtawarira and Genia played in the Barbarians' 2009 victory over New Zealand.
"We're delighted that these four established international players will be joining us when we take on Argentina," Barbarians chairman John Spencer said.
"It's a reflection of the enduring reputation of the club that we are able to attract greats from around the globe to come together and play with skill, flair and enjoyment."
The December fixture follows a round of Autumn International Tests. Springboks' prop Mtawarira, lock Etzebeth and fly half Pollard face England, France, Scotland and Wales across October and November while Genia faces Wales, Italy and then England for Australia.
The remaining members of the Barbarians team will be named over the coming weeks.