New Zealand fly-half Aaron Cruden said it was a "tough pill to swallow" after learning he could miss the Rugby World Cup through injury.
The 26-year-old, capped 37 times, tore cruciate ligaments in his left knee while playing for Waikato Chiefs.
He will have a knee reconstruction and is expected to be out for six months.
New Zealand's first match at the World Cup - against Argentina at Wembley - will be played on 20 September, with the final on 31 October.
"I wasn't too sure what it was when it happened," said Cruden, who told the All Blacks website he had not given up hope of playing at the World Cup.
"It was hard to believe when I heard what it was. There was no swelling around the knee and it still feels reasonably strong.
"It felt like I had been struck down by a sniper."
Cruden, who has scored 280 points for the All Blacks, made his most recent international appearance in the 24-21 win over England in November.
He was the starting fly-half for New Zealand's 2011 World Cup final triumph after Dan Carter and Colin Slade sustained injuries.
Cruden went off in the first half of the 8-7 win over France with a knee injury, leaving Stephen Donald - who had been on a fishing holiday at the start of the tournament - to kick the decisive penalty.