All Blacks great Sam Whitelock will set a new record of 149 New Zealand caps if he takes to the field off the bench against Italy in the Rugby World Cup.

The 34-year-old will gain sole possession of the record he equalled earlier this month of his 2011 and 2015 fellow World Cup winner Richie McCaw. 

Only Alun Wyn Jones of Wales, with 171, has made more international appearances than Whitelock and McCaw. 

Although he will start on the bench against the Azzurri in Lyon, he has been driving on his teammates and trying to outperform the starters.

"It's obviously his 149th cap and to be able to do that from a physical and a mental side, to be able to turn up every week and prepare and play the way he does is a testament to him," Brodie Retallick, who will start at lock alongside Scott Barrett, said on Thursday.

Retallick and Whitelock have partnered up in the second row many times together over the years.

Aged 32, Retallick is himself a Test centurion with 105 caps to his name.

Whitelock was already an international player when Retallick was first picked for the All Blacks, and his teammate has been driving him on ever since.

"The biggest impact he's had was when he was the established number one lock in the All Blacks before I was," said Retallick.

"Just the competition to keep getting better and keep at his level, he's done that for so long and obviously that's the best achievement you can get.

"Just by doing that and having that competition, even if this week he's been named on the bench, he's still pushing everyone around the field and trying to outdo everyone.

"Playing in a lot of Test matches with him has been special but the competitiveness he has throughout training, week in, week out is a big benefit."

It is that love of competition that has kept Whitelock going for so long.

Barrett said that when Whitelock inevitably replaces one of the two second rows against Italy he will do what he always does: compete hard.

"Sam (is) bringing up a huge milestone that's never been done in an All Blacks jersey," said Barrett.

"It's been a huge honour and privilege to play alongside him throughout my career.

"I'm sure when he gets out here (on Friday) he'll do what he does every time he pulls on the jersey, and that's play tough rugby."

bc/pi