The Black Caps have cut all-rounders Mitchell Santner and Daryl Mitchell from their squad for the World Test Championship final against India.

The pair played one test apiece in New Zealand's series win over England, but aren't wanted for the final, with the squad being trimmed from 20 players to 15 ahead of the test which starts on Friday.

Also missing out from the extended squad are Doug Bracewell, Jacob Duffy and Rachin Ravindra, a trio that didn't play in the England series.

Santner's omission leaves Ajaz Patel as the sole spinner in the squad, while Colin de Grandhomme will be the all-round option, with the possibility that both could play against India, at the expense of a frontline seamer.

Will Young and Tom Blundell are part of the squad as batting and wicketkeeping cover, while Matt Henry is the additional fast bowler in the mix.

Patel was given a start in the second test at Edgbaston after Santner suffered a finger injury, and the 32-year-old impressed, taking four wickets and producing eight maidens in 23 overs as he deftly mixed control with aggression. A solid lower-order contribution of 20 would have slightly helped his cause as well, but Black Caps coach Gary Stead explained that the English conditions also played a significant role in Patel getting the nod over Santner.

"Ajaz bowled beautifully – in both innings he did the role we wanted him to do, and picked up a couple of key wickets," Stead said.

"The conditions we face here in England are slightly different from a spin perspective to what we get in New Zealand, I think the wickets here deteriorate a little bit faster so the role of the spinner is probably a little bit more of an attacking option than what it is in New Zealand.

"We felt we needed to have what we thought was our best spinner in terms of the guy who can take wickets for us, and that's why Ajaz got that nod."

Stead also provided positive news about the status of skipper Kane Williamson and wicketkeeper BJ Watling, who both missed the second England test with niggling injuries.

"I'm pleased to be able to say that Kane and BJ both batted and did their drills – they got through that really well. It's been really pleasing to see the movement of both of them in a positive direction. All signs at this stage are leading to them being available."

De Grandhomme is also fit and ready, with Stead elaborating on how they managed his workload.

"We made a decision not to play Colin in the last game as we felt if we wanted him to be in contention for this match, the loading that he would have had, considering he had an operation on his ankle as well, would have just been too big. We made the call to de-load him slightly in the last week and getting him ready for what could be him playing in the match."

The removal of Santner and Mitchell from the equation, with Henry also likely to miss out, leaves three likely scenarios for Stead and Williamson to ponder.

The first sees de Grandhomme play at the expense of Patel in an all-seam lineup, while the reverse would see de Grandhomme benched in a bowling-heavy lineup featuring Kyle Jamieson batting at seven.

The final, and perhaps most likely option, would result in both de Grandhomme and Patel playing, with the selectors then having to make an extremely tough call in cutting one of Jamieson, Tim Southee, Neil Wagner or Trent Boult from the XI.

However, having only arrived in Southampton today, Stead is holding off on his toughest selection decisions until there's more clarity surrounding the weather and the pitch.

"There could still be a whole lot of different scenarios depending on what the pitch looks like, what the weather looks like. The weather forecast looks a little bit dodgy heading into the game so that may have an impact on our final decisions – we'll judge that a little bit closer to the time."

Black Caps squad for the World Test Championship final: Kane Williamson, Tom Latham, Devon Conway, Will Young, Ross Taylor, Henry Nicholls, BJ Watling, Tom Blundell, Colin de Grandhomme, Kyle Jamieson, Matt Henry, Tim Southee, Neil Wagner, Ajaz Patel, Trent Boult.