New Zealand face being without Dane Coles for the first test against the British and Irish Lions on 24 June, with the hooker unable to train due to suffering from symptoms of concussion. The 30-year-old has not played for his club side the Hurricanes since March due to separate knee and calf problems however his return to training has been postponed because of exercise-inducing headaches – an indication he has picked up a head injury.

However, confusion reigns at the Super Rugby franchise with none of the medical team or Coles able to identify when he suffered the trauma. Club officials have re-watched his last outing against the Highlanders on 18 March but are yet to detect a possible trigger for the concussion.

Dane Coles
Coles played in 13 of New Zealand's 14 tests in 2016 and is expected to play an integral role this summer. Reuters

Having not played for nearly seven weeks and with no date set for Coles' return to training, the New Zealand front row forward is unlikely to match fit in time for the first of three tests against the Lions starting next month. Hurricanes head coach Chris Boyd is mystified over the fitness concern which remains unresolved.

"We genuinely don't know where he got those symptoms from, but those symptoms were not apparent to us until post his return-to-train from his knee injury," he said. "So he had no symptoms post that game, if in fact he incurred the injury in the game.

"We can't load his calf because he's getting headaches and in the end I'm not sure whether his concussion symptoms are going to go away first or whether his calf issue is going to go away first, but we can't test the calf until they do.

"No [Coles has no idea]. We've had a look at the Highlanders game, which was the last game he played. There's no obvious point in time, he had no symptoms post that, so I'm not sure. I don't think there's any smoke and daggers there. I think at the end of the day he's started to return to train and developed some headaches."

Coles is among a lengthy All Blacks injury list with less than eight weeks to go until they face the Lions in Auckland. World Cup winners Kieran Read [broken thumb], Jerome Kaino [knee] and Nehe Milner-Skudder [foot] are each facing a race against time to be fit, giving coach Steve Hansen several selection dilemmas ahead of the series against Warren Gatland's side.