Super Rugby 2019: All Black Ryan Crotty under concussion cloud in Crusaders win

All Blacks midfielder Ryan Crotty may face time on the sidelines, after leaving the field with concussion in the Crusaders' Super Rugby win over the Lions.

Crotty started at second-five in the 36-10 victory, but took a head knock and was replaced by Mitch Hunt during the first half.

Although he passed his head injury assessment (HIA), coach Scott Robertson decided not to risk his backline kingpin and kept him out of further action.

The 44-cap international already has a history of concussion and Robertson wasn't prepared to risk him with so much depth to call on.

"He did pass his HIA, but we decided the best thing for him, with his history... it was commonsense for us to say 'you're good', but the best thing for him was to make a decision and sub him," explained Robertson afterwards.

Ryan Crotty looks for support against the Lions
Ryan Crotty looks for support against the Lions. Photo credit: Photosport

Crotty's vulnerability to head injury may yet prove a factor in the All Blacks World Cup selection, where coach Steve Hansen has a surplus of midfield talent to call on.

Already faced with the requirements of a player-welfare protocol and coming off a bye, Robertson chose to rest three internationals - lock Scott Barrett, flanker Matt Todd and centre Jack Goodhew, along with injured prop Owen Franks - an extra week against the Lions.

Afterwards, he hinted more could be spelled against the Sharks at home, before the two-time defending champions embark on their South African road trip next month.

Given the caution around Crotty, he may well be sitting in the stands next Friday.

"We were fortunate to have that bye week and give a bit of time to those All Blacks to really refresh on our terms," he said. "If something happens, we've got guys that can play.

"Sometimes, when you factor it in, you get a couple of injuries and you do have to rest them, it puts a lot of pressure on you."