They are becoming increasingly important to the All Blacks due to their experience, consistency, and the fact that, apart from Tuipulotu there is a big gap to the next best.
If he is ruled out, it's likely Hurricanes lock James Broadhurst will quickly enter the frame.
Tuipulotu has a rare mix of athleticism and power and the Blues scrum has been better for his presence this season but he will almost certainly not play for John Kirwan's team again this year.
The All Blacks selectors have taken a pragmatic approach into this Super Rugby year ahead of their World Cup defence. They have expected injuries and they are getting them.
Aaron Cruden has already been ruled out due to knee surgery, with Beauden Barrett's knee problem giving them a further scare.
Barrett will be back in a matter of weeks, with Chiefs lock Retallick expected back next week after a four-week break due to a shoulder problem.
Blues skipper Jerome Kaino's dislocated finger is another potential headache for the national selectors, although his eight-week rehabilitation period after his surgery a fortnight ago is thought to be very much worse-case scenario.
Kaino suffered his injury - a compound dislocation of the ring finger on his left hand - in the victory over the Force at Eden Park on May 2. Chiefs midfielder Sonny Bill Williams was last night ruled out of tonight's match against the Hurricanes with a back injury.