Sonny Bill Williams (Getty Images)
Rio de Janeiro - Sonny Bill Williams warned on Wednesday he had transitioned into a complete rugby sevens player, a move that has proven a step too far for many other 15s stars eyeing Olympic glory.
Williams, 30, was an outstanding rugby league player before swapping codes for union, going on to win two Rugby World Cups (2011, 2015).
A brief spell as heavyweight boxing champion of New Zealand is also part of the towering centre's resume, with a chance of Olympic gold in the debuting rugby sevens proving too tempting to pass on.
"Having no sevens experience coming into this year, I sat down at the start with the coach (Gordon Tietjens) and we spoke about it and the key was putting myself in the sevens environment through the whole year, to learn off my teammates and to become a sevens player," Willams said.
"I definitely feel like I have now. The fitness levels are up where they should be and the knowledge of the game as well."
Williams was last week named in the All Blacks squad for the Rugby Championship also featuring Argentina, Australia and South Africa.
But he insisted there would be no problem fitting into Steve Hansen's plans, with a likely outing against the Wallabies his first 15s experience after the Rio sevens.
"It's always a proud moment to be named in the All Blacks side and I don't take that for granted.
"But my time spent in the sevens environment is only going to help me going back to 15s," he said, highlighting fellow All Black and former sevens star Ardie Savea and Super Rugby winger Reiko Ioane, currently in Rio with Williams.
OLYMPICS SURPASS WORLD CUPS
Despite being part of the All Blacks squads that claimed back-to-back World Cups, on home soil in New Zealand and then England, Williams said an Olympic gold medal would outrank those achievements.
"I guess it would have to surpass it because as an athlete there's no higher level than the Olympics," said Williams, whose sister Niall will turn out for the New Zealand women's team in Brazil.
"I'm just fortunate enough that (coach) Titch gave me a shot at the start of the year, to learn off the team and train my butt off. We just want to be successful."
He added: "I always knew it was going to be tough, but it was really hard. It's a totally different game to 15s.
"There's been a lot of 15s players who've tried to make the sevens team but they haven't made it because it's a totally different game. That's why I'm thankful I sat down with Tich at the start of the year and we sussed out a plan to put me forward for the whole year to try to crack it."
Veteran sevens player Tim Mikkelson said Williams had proved any sceptics wrong.
"When he first came we didn't know what to expect," Mikkelson said.
"He's very physical in the games and in training. He's just improved in every training and his fitness has got better."