All Black legend Jonah Lomu's death was most likely caused by a blood clot on a lung associated with air travel back to New Zealand.
That was the word from former All Blacks doctor and close friend of Lomu, doctor John Mayhew who made the revelation in an interview with the BBC.
40-year-old Lomu died last week after a long battle with a chronic kidney condition.
"He returned from the UK via Dubai and appeared to be in good health before he died," Mayhew told the BBC.
"We think the most likely cause was a clot on the lung which can be a complication of long distance travel.
"Jonah was at greater risk of that happening because of his renal condition.
"The other possibility is a cardiac death, but on the balance of probabilities it was probably a massive clot on the lung."
Mayhew also said Lomu's death would have been "instantaneous".
"Soon after, we tried to resuscitate him, but he was comfortable and I think it was instantaneous," he explained.
"He was unaware of what had happened.
"It's just one of those tragic complications that can occur in people with chronic renal conditions."
Meanwhile, New Zealand Prime Minister John Key has announced Lomu's memorial service details. A public service will be held in Eden Park on Monday November 30.