England wicketkeeper-batsman Jos Buttler is a doubt for the second Test against New Zealand after suffering a back spasm.

Buttler sustained the injury in training and could miss the final match of the series against the Black Caps at Seddon Park, which starts on Friday.

Ollie Pope will take the gloves if Buttler is ruled out in Hamilton, where the tourists need a victory to salvage a 1-1 draw after they were hammered by an innings and 65 runs in Mount Maunganui.

England captain Joe Root said: "Jos has tweaked his back in the gym. We'll have to find out a little bit more information on that throughout today and see where he's at."

Root suggested England could select an extra bowler if Buttler is unable to play.

"There's a number of different combinations we could go with and I think a lot of that will rely on the surface," the batsman added.

"Trying to find the best combination, which would take 20 wickets, and then balancing that in terms of getting the batting where we want it to be. It could be an allrounder, we'll see."

Hamilton-born all-rounder Daryl Mitchell will make his Test debut for New Zealand in place of Colin de Grandhomme, who suffered an abdominal tear.