It's a squad game. And especially so when you have to play at altitude.
Ireland head for the hills of Ellis Park for Saturday's second Test against South Africa and Joe Schmidt has decided to freshen up his side as he seeks the formula for a victory that would secure a historic series win.
Schmidt has made five changes from the side that won so impressively in Cape Town last Saturday.
In come Tadhg Furlong, Quinn Roux, for his debut, Rhys Ruddock, Stuart Olding, and Craig Gilroy.
Iain Henderson moves from the second row to blindside flanker. Conor Murray and Paddy Jackson get a chance to build on their partnership at 9 and 10.
CJ Stander is suspended while there is no place in the 23 for Ultan Dillane.
But will it be good enough to make it two wins from two?
IRELAND TEAM FOR SECOND TEST V SOUTH AFRICA
15. Jared Payne
14. Andrew Trimble
13. Robbie Henshaw
12. Stuart Olding
11. Craig Gilroy
10. Paddy Jackson
9. Conor Murray
1. Jack McGrath
2. Rory Best
3. Tadhg Furlong
4. Devin Toner
5. Quinn Roux
6. Iain Henderson
7. Rhys Ruddock
8. Jamie Heaslip
Replacements
16. Richardt Strauss
17. David Kilcoyne
18. Finlay Bealham
19. Donnacha Ryan
20. Sean Reidy
21. Kieran Marmion
22. Ian Madigan
23. Tiernan O'Halloran
South Africa have also named their side as they seek to bring an end to the huge amount of criticism that has been coming their way since Saturday's defeat.
SOUTH AFRICA: Willie le Roux; JP Pietersen, Lionel Mapoe, Damian De Allende, Lwazi Mvovo; Elton Jantjes, Faf de Klerk; Tendai Mtawarira, Adriaan Strauss (capt), Frans Malherbe; Eben Etzebeth, Pieter-Steph du Toit; Francois Louw, Siya Kolisi, Duane Vermeulen. Replacements: Bongi Mbonambi, Trevor Nyakane, Julian Redelinghuys, Franco Mostert, Warren Whiteley, Rudy Paige, Morne Steyn, Ruan Combrinck.
