Former All Blacks turned Warriors doctor John Mayhew is surprised World Rugby has been forced into a change.

Loose forward Sam Cane wasn't allowed to return to the field in the rugby World Cup win over South Africa.

He passed the concussion test, but was deemed to have exceeded the time limit around the HIA protocol.

John Mayhew told Mike Hosking that Sam Cane should have been allowed to return to the field in his side's Rugby World Cup opener.

“To me it looks like he was fit to play and it was an administrative error.

“It’s very disappointing and it shouldn’t happen at the biggest Rugby tournament in the world.”

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