Barbarians head coach David Young, the current Cardiff Blues boss and former Wales and British and Irish Lions prop, has announced the first six high profile names in his star-studded invitation squad, with Italian talisman and captain Sergio Parisse the final name on the current list.
Young is relishing the prospect of leading the Baa-baas at Wales' national stadium in this 130th anniversary celebration match of the Welsh Rugby Union.
The game will form a vital part of Wales' preparations for the 2011 Rugby World Cup in New Zealand and Young believes his 'dream team' squad will be able to provide the ultimate test to his opposite number, Wales head coach Warren Gatland, and his squad.
"We have the spine of a pretty impressive line-up already and there will be plenty more names in the coming weeks which will whet the appetite for what should be a spectacular game of rugby," said Young.
"It will be interesting for me personally coaching against Wales and against a side with probably many of my own regional squad players in it.
"But Barbarians rugby is infectious and when you get that many class players in a changing room they are all winners through and through and the coach's job is made easy.
"I'm particularly looking forward to fielding a back row with Parisse and Smith playing together and, knowing who we plan to slot in alongside them, it's going to be a pretty exciting trio.
"John Hayes has been a thorn in the side of many Welsh teams in the past and you can't ask much more than having three World Cup winners to choose from in your backline."
Steyn, currently plying his trade in France with Racing Cub and Piennar, starring for Ulster in the Magners League, were both part of the Springboks 2007 RWC triumph.
The 36-times capped Steyn, who also plays at fly-half and wing, started the 2007 final at inside centre and became the youngest player to lift the World Cup.
Piennar, who was also a member of the '07 squad plays at scrum-half or fly-half and has amassed 43 caps for his country.
Both players could face Wales again for South Africa as RWC 2011 Pool D opponents if selected for the Springboks later this year.
Balshaw was part of the English 2003 RWC winning squad, appearing in the final as an extra time replacement to earn his medal.
Wales assistant coach Rob Howley added: "This is a huge game for Wales, vital to our preparations for the Rugby World Cup and I'm delighted by the decision to award full Test caps for the match.
"This game is an opportunity for players who may have been on the fringe of our squad, but also a huge opportunity for us to bounce back from the result against France and for the guys who played in that game.
"On a personal level Barbarians rugby is very close to my heart in my own career, it's a tradition that is steeped in history in the rugby world and we are so delighted as a management team just seeing some of the names that have been put forward for selection for that game.
"Sergio Parisse, George Smith, Francios Steyn, Ruan Piennaar, we are talking about some of the greats of the world game and I think that the players who are selected for Wales to play against the Baa-baas will have no doubt that they will be up against world class players.
"We are delighted, also, to see Dai Young coaching the Barbarians, he is a very good friend and we have a huge amount of respect for his coaching ability and the challenge is one we are very much looking forward to.
"It's the next game for us and that's the important part of RWC preparation, you have to take that competition game by game, the match also gives us an opportunity to look at our own squad and the players putting themselves forward for RWC selection.
"The way the Barbarians play, it's traditional open rugby, when you look at their results as the game has gone professional they have sometimes found it hard to get the structure to their game because of the amount of time available.
"Their game is based on skills of players and talent and, as we have mentioned, their players certainly have the talent and are going to be capable of playing good 'off-the-cuff' rugby."