Ben Smith's repeated concussions are concerning the All Blacks.

Smith, the All Blacks vice-captain and fullback, suffered his third knock in recent times in the All Blacks 30-15 victory over the Lions on Saturday at Eden Park. He left the field after 27 minutes, did not return, and has now been replaced in the squad by Chiefs utility Damian McKenzie.

Given Dane Coles has now been sidelined for the best part of four months with concussion, All Blacks coach Steve Hansen admitted there were worries for Smith and every precaution would be taken.

HANNAH PETERS/ GETTY IMAGES Chiefs utility Damian McKenzie has been added to the All Blacks squad as cover for the injured Ben Smith.

"Obviously there's something going on there that's not quite right so we need to find out what that is," Hansen said.

"It's like any concussion until such time as he goes through all the protocols and passes them he's not going to be available. It's day one and he's still to go through anything in regards to testing. It's not the sort of thing you rush into. We'll give him a few days. "

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On Saturday Hansen revealed that while Coles had returned to training and was over his concussion symptoms, he would play no part in the Lions series.

"He definitely won't play for us and probably won't play for the Hurricanes in that first week or maybe two weeks but if they continue on into the competition he should be ready."

Ryan Crotty is another casualty, with Hansen saying his hamstring injury would keep him out for anywhere between two and four weeks. Crusaders centre Jack Goodhue will, therefore, remain with the squad as cover, with Sonny Bill Williams and Anton Lienert-Brown expected to team up again in the midfield.

FIONA GOODALL/GETTY IMAGES Ben Smith suffered a head knock in the All Blacks' win over the Lions at Eden Park.

Matt Todd, on stand-by as injury cover, tweaked his calf during the week. Akira Ioane will travel with the All Blacks to Wellington to ensure they have enough loose forwards available with Liam Squire more likely to recover from his broken thumb for the third test in Dunedin.

The All Blacks have, meanwhile, released Julian Savea, Jordie Barrett, Vaea Fifita and Ngani Laumape to the Hurricanes for their match against the Lions in the capital on Tuesday.

"The reason we are letting them play is this event is only once every 12 years. It wouldn't be fair on them not to allow them to play and then not play them in test matches. We don't know what's going to happen over the next couple of weeks selection wise. All of them will grow in experience. Apart from Julian they're all young players so the hit-out against the Lions will be great for them and their careers and it's something I think we need to honour as best we can.

"Lions tours are important. We don't want to lose them. You saw last night they create a great test match but their fans bring a lot too. They're outstanding in their enthusiasm. They even get us a little bit excited as New Zealand fans. They force us to get out of our shell and get boisterous and do things that as Kiwis we don't normally like doing.

"It's an occasion and something we don't want to lose."