Hansen backs rookies to front up

All Blacks coach Steve Hansen has expressed his faith in rookies Jordie Barrett and Ngani Laumape ahead of the decisive third Test against the British and Irish Lions.

Barrett and Laumape have been thrown into the mix after Rieko Ioane and Waisake Naholo were ruled out with illness and concussion respectively while Sonny Bill Williams is suspended for his red card in the second Test.

Although the more experienced Malakai Fekitoa was called up as cover after Williams' indiscretion, Laumape has got the nod to start at inside-centre. Julian Savea and Israel Dagg take up the wing positions while Barrett slots into full-back.

Only his second appearance and only twenty years old, Hansen has shown immense faith in the precocious Barrett.

"Whatever he does on Saturday, it's just the beginning. He's only going to get better and better," Hansen told the AAP.

He's a good defender when he gets his positioning right. We've worked hard on that with him.

"Do we have confidence? We wouldn't have picked him in the first place if we didn't."

Meanwhile, Hansen has explained his reasoning for picking Laumape over Fekitoa at inside centre.

"Ngani's all-round game, we think, is slightly better than Mala's. That's why we picked him in the first place," Hansen said.

"He's probably getting pushed up the ladder a little quicker than we want but he's an experienced athlete who's played a lot of big-time football for various other codes.

"We're very confident that he'll front up."