The eight previous Lions in the squad are Shane Williams, Ronan O'Gara, Andrew Sheridan, Simon Shaw, Paul O'Connell, Martyn Williams, Phil Vickery and Stephen Jones, who have 546 international appearances between them.
Tour manager Gerald Davies said: "After all the preparation the match against the Royal XV on Saturday marks the start of the 2009 tour. Everyone in the tour party is looking forward to getting the playing part of the tour underway."
Nine players will make their Lions run-on debuts including the centre pairing of 21-year-old Irishman Keith Earls, who is the youngest player on tour in South Africa, and 22-year-old Welsh centre Jamie Roberts.
Commenting on the team selection, head coach Ian McGeechan said: "I think it is really exciting that we have a lot of players making their debuts. I remember my debut against Western Transvaal at Potchefstroom in 1974 and it is a career highlight.
"For young men such as Keith Earls and Jamie Roberts it will be a day to remember and they will be thrilled to get an early taste of match action on the tour.
"Outside these guys is the proven experienced combination of the Ospreys' back-three of Lee Byrne, Tommy Bowe and Shane Williams.
"While we have a lot of players making their Lions debuts there is a huge amount of international experience in the team. The average age is 28 and that reflects the maturity we have in the squad.
"On Saturday we have in the team, Martyn Williams, Ronan O'Gara and Simon Shaw who are on their third Lions tours.
"They know exactly what is in store in terms of the provincial matches. Scottish captain Mike Blair is at scrum half while players of the calibre of Paul O'Connell, Joe Worsley and Adam Jones have played over 50 Tests each.
"Following excellent preparation and a period of acclimatisation in South Africa I know the lads are raring to go on Saturday against the Royal XV and will be anxious to get the tour off to the best possible start," McGeechan added.
BRITISH & IRISH LIONS TEAM/REPLACEMENTS (v Royal XV, 2009 Lions Tour, Saturday, May 30, Royal Bafokeng Sports Palace, kick-off 3pm local time/2pm Irish time):
15. Lee Byrne (Ospreys/Wales)
14. Tommy Bowe (Ospreys/Ireland)
13. Keith Earls (Munster/Ireland)
12. Jamie Roberts (Cardiff Blues/Wales)
11. Shane Williams (Ospreys/Wales)
10. Ronan O'Gara (Munster/Ireland)