The loose forwards have had a real shakeup.
Kieran Read is resting after a repeat head knock and concussion, Victor Vito is still injured and Adam Thomson is on the bench after he took a battering in Christchurch.
New squad member Liam Messam will play on the blindside, his Chiefs teammate Sam Cane starts on the openside with McCaw switching to the back of the scrum.
The 105-test flanker has started all the internationals in his decade-long career on the open side but injuries have forced the change.
This will be his 100th test start and only two other forwards Victor Matfield (105) and Jason Leonard (104) have started more internationals.
The alterations continue on the bench with hooker Keven Mealamu restored after his calf muscle problems and newcomer Beauden Barrett and one test utility Tamati Ellison into the back reserves.
Coach Steve Hansen said his side's narrow 22-19 win at Christchurch was a tough, high-pressure test.
"It said a lot about the character of both teams and I believe this third test will see the same character and composure needed," he said.
"The All Blacks by their own admission weren't happy with the way they performed, and in part this is a credit to the way the Irish played.
"They have laid down a challenge and the key will be how we respond."
Three Smiths in the side will test the commentators and Ben Smith should bring better defensive solidity under the high ball which was exposed by a better Irish kick-chase game in Christchurch.
Cruden's promotion on his home patch will also put him in tune with Sonny Bill Williams and the work they have done this year to torment opposition defences.
Similarly Cane and Messam should be in sync after games with the Chiefs.
It may be that McCaw wears the No 8 uniform but leaves some of the backfield work to Messam who is more familiar with those duties.
The work at the back of the scrum which came under some late heat last week will also put McCaw's game under more scrutiny.
In the tight five Romano leapfrogs out of the non-players group to a starting role alongside his Crusaders teammate Sam Whitelock.
Romano should bring some grunt to the right side of the scrum and should feel comfortable in a pack which contains half of the Crusaders' Super 15 forwards.
Starting XV (test caps):
1. Tony Woodcock (85)
2. Andrew Hore (64)
3. Owen Franks (33)
4. Luke Romano *
5. Samuel Whitelock (27)
6. Liam Messam (9)
7. Sam Cane (1)
8. Richie McCaw - captain (105)
9. Aaron Smith (2)
10. Aaron Cruden (11)
11. Hosea Gear (8)
12. Sonny Bill Williams (16)
13. Conrad Smith (57)
14. Ben Smith (4)
15. Israel Dagg (14)
Reserves:
16. Keven Mealamu (92)
17. Ben Franks (17)
18. Brodie Retallick (2)
19. Adam Thomson (26)
20. Piri Weepu (58)
21. Beauden Barrett *
22. Tamati Ellison (1)