Sir Graham Henry and grief-stricken teammates of former All Black Sione Lauaki were shocked to learn the bustling forward had died from apparent kidney and heart failure.
Former All Blacks coach Henry told the Herald the 35-year-old's death overnight came as a surprise.
"I don't think anyone suspected this - some of the players may have known - but it's just very sad, you don't expect anyone his age to have heart problems. It's very sad for his wife and family."
Lauaki, who stood at more than 6ft 4in (1.92m), was diagnosed with kidney and heart problems in 2012, forcing him to stop playing professional rugby for Top 14 club Bayonne after initially moving to France to play for Clermont Auvergne in 2010.
He was reported to be living in Rarotonga with his wife following his retirement from rugby.
Henry indicated there were no signs Lauaki had serious health problems during his tenure with the All Blacks from 2005 to 2008.
"We didn't know at the time, and like [the late] Jonah [Lomu] he probably didn't know either. Sione didn't know, and we didn't know."
The former principal of Kelston Boys' High School was coaching Wales when Lauaki emerged from the same school as a destructive player, making his debut for Auckland in 2002.
The Tongan-born forward played 17 tests, was part of the squad for the 2007 World Cup, and started at No 8 during the third test of the 2005 British and Irish Lions tour to New Zealand.
"He was a big boy, a big No 8, touching on 120kg, that was his best position - a very explosive player," Henry said.
The world champion coach said Lauaki, who played against Italy, Portugal, Scotland and Romania during the 2007 tournament, had "outstanding ability" and was "very popular".
"The problem was he had Rodney So'oialo and [the late] Jerry Collins ahead of him [on the depth chart] as loose forwards, and he found it hard to break in."
After some fitness and commitment doubts early in his professional career, Lauaki began gaining attention after his debut for the Chiefs in Super Rugby in 2004, and his test debut against Fiji at Albany in 2005.
He played for the one-off Pacific Islanders combination, and scored tries for the team against Australia, New Zealand and South Africa during a 15-day period in 2004.
Lauaki also had issues off the field, resulting in several court appearances.
In February 2006 he admitted assaulting a security officer in Hamilton, while in January 2009 he was ordered to undergo anger management courses after trashing an Auckland motel.
His problems continued in June 2010 and he was convicted of careless driving and assault after punching a man twice in the mouth at a Hamilton bar, and later in March 2014 he was convicted of willful damage after ripping out a CCTV camera in an Auckland taxi.
However, former teammate and All Blacks fullback Israel Dagg told Newstalk ZB Lauaki was a "quiet man".
"But on the field, he was absolutely dominant . . . I've got this video in my mind of when he absolutely threw [former All Blacks captain] Richie McCaw 10 metres.
"He was a big man with a big heart and had a lot of time for everyone."
The Chiefs paid tribute to Lauaki, who was capped 70 times for the Hamilton-based franchise, by dedicating the rest of its Brisbane Global Rugby Tens campaign to the athletic back-rower.
Chiefs captain Liam Messam was given permission to fly home immediately after the team's scheduled quarter-final against the Queensland Reds.
"There's a number of guys who played a lot of footy with Wax," Chiefs coach Dave Rennie said.
"Liam Messam, in particular, is a great mate of his so it's been a pretty upsetting morning."
New Zealand Rugby CEO Steve Tew also expressed his condolences and said with Lauaki passing at such a young age "it will be felt with an even greater sense of tragedy".
Several other All Blacks, including Dan Carter, Piri Weepu, Cory Jane, Adam Thompson and Sonny Bill Williams also left tributes to Lauaki on social media.
Wallabies stars Matt Giteau and Israel Folau equally paid their respects to Lauaki.
Lauaki's brother Epalahame Lauaki played for the New Zealand Warriors in the NRL and Hull, Wigan, and Bradford in the Super League.
-Additional reporting AAP