Wellington Firebirds opener Finn Allen has been placed on stand-by for his international debut with out-of-form veteran Martin Guptill getting the nod for the upcoming Twenty20 series against Australia.

Despite Allen scoring 512 runs at a strike rate of 193 in the Firebirds' Super Smash title run, Black Caps selectors have gone with Guptill if he passes a fitness test.

The five-match series begins at Hagley Oval on February 22.

Guptill missed the final two games of the Super Smash season with a hamstring injury, but will assemble with the squad in Christchurch on Friday in order prove his fitness for the series.

The Auckland Aces and Black Caps veteran has lacked form this summer, scoring 46 in his three T20 innings against Pakistan before making three single-digit scores in his last four Super Smash innings.

In contrast, Allen scored six half centuries in the Super Smash with an average of 56.88. He may have to wait until the Bangladesh series in March for his next chance to make his debut.

Although Allen won't assemble with the side, Black Caps selector Gavin Larsen made it clear the 21-year-old's weight of runs in the Super Smash had not gone unnoticed.

"Finn's been in outstanding form and he's certainly an exciting talent," Larsen said.

"Martin's our incumbent opener and our highest T20 International run scorer so we're backing him to do the job at the top of the order, but he will need to prove his fitness and it's good to know we have a ready replacement in Finn on stand-by."

Colin Munro also misses out after the 33-year-old chose to play in the Australian Big Bash League for the Perth Scorchers this summer, instead of Auckland in the local Super Smash.

Batting at three for much of the Big Bash, the left-hander was consistent, making three consecutive half-centuries and four in five innings as the Scorchers overcame a horror start to rocket into title contention, before finishing runners-up to the Sydney Sixers.

Munro averages 31.3 at a whopping 156 strike rate for the Black Caps in the shortest form, but hasn't represented his country for over a year.

There's a familiar look to the Black Caps squad with batsmen Devon Conway, Glenn Phillips and Mark Chapman backed to continue in the middle order after strong starts to the international season.

Trent Boult, Tim Southee, Kyle Jamieson and Hamish Bennett make up the pace-bowling quartet, with Mitchell Santner and Ish Sodhi the spinners, while Jimmy Neesham has overcome his finger injury to be named as the all-rounder.

Black Caps T20 squad
Kane Williamson (c)
Hamish Bennett
Trent Boult
Mark Chapman
Devon Conway
*Martin Guptill (pending fitness test)
Kyle Jamieson
Jimmy Neesham
Glenn Phillips
Mitchell Santner
Tim Seifert (wk)
Ish Sodhi
Tim Southee