Northern Districts all-rounder Daryl Mitchell has been called into the squad as a replacement for de Grandhomme and will probably play while Lockie Ferguson and Matt Henry, already part of the squad, are vying to replace Boult. At this stage, it appears Henry is the more likely to play.
Boult was unable to bowl more than a single over on the final day of the first Test after reporting pain in his side. He underwent an MRI scan on Tuesday with the results showing he had strained one of the muscles overlying his ribs on his right-hand side. Meanwhile, De Grandhomme has been diagnosed with a tear to his left lower abdominal muscle, sustained during England's second innings at Bay Oval.
While there is, naturally, disappointment in the New Zealand camp about the injuries, there is perhaps also a hint of relief about the results of Boult's scan. It cleared him of any bone stress and the team management is still hopeful he could recover to play at least some part in the Test series in Australia. New Zealand depart for Australia on December 7, with the first Test starting in Perth on December 12.
"It's as good as it can be, so hopefully they won't be out for too long," Shane Jurgensen, the bowling coach, said. "We want them on the plane to Perth. So it's a case of rest and rehab for them over the course of this Test. Trent will doing physio five times a day for the next week. He'll be sleeping with the physio. Hopefully it will be quite a quick rehab.
"Colin has this habit of coming on and getting wickets. Maybe he leads them into a false sense of security because he's a bit slower with his pace but he bowls a heavy ball, he's accurate and he's skilful. He can exploit any grass on a surface or he can hold up an end."
The absences could result in two Test debutants in Hamilton on Friday. Mitchell has played nine T20Is but never been part of a Test squad before, while Ferguson has been pushing for selection for some time. It appears at this stage, however, as if New Zealand might recall Henry who has played 10 Tests and would have been encouraged by a first view of the green-tinged surface at Seddon Park.
"It's a fantastic opportunity for Daryl if he's selected," Jurgensen continued. "He bowled quite well when I looked after the A team recently. I think he's the capability to do what Colin has in recent times. We're lucky we have Daryl to come in."
Todd Astle, the leg-spinner, has also been recalled to the squad having been released to play a couple of limited-overs domestic games for Canterbury in recent days. At this stage, however, it seems unlikely he will play in Hamilton.
"I was really proud the way the guys bowled in the first Test," Jurgensen said. "That wicket was dry and flat - not what we'd normally see in New Zealand - so it took a really combined team effort. Tim Southee took four wickets in the first innings; Neil Wagner took five in the second and Mitchell Santner came through and got the ball rolling.
"Henry has done a really good job for the team and is a genuine new ball bowler. And so, too, is Lockie. Both options will be considered. You always want to give people an opportunity to play. But it is Test cricket and we pride ourselves on playing the best XI.
"This pitch tends to offer a bit for the fast bowlers and the seamers. Then, if it gets hot, it becomes a pretty good pitch. But the ball tends to swing here as it's a bit more humid than other places. You probably have to look up above rather than at the pitch."
New Zealander were boosted further by Wagner's rise to No. 3 in the Test bowling rankings; a highest ever position for him. Boult is placed at No. 11 and Southee at No. 14. New Zealand also have three men (Kane Williamson at No. 3, Henry Nicholls at No. 6 and Tom Latham at No. 8) in the top 10 of the batting rankings.