Aaron Cruden's hopes of featuring at the 2015 World Cup have been dealt a potentially fatal blow after the New Zealand fly-half suffered a nasty injury during the Chiefs' victory over the Crusaders on 17 April.

The 26-year-old, a long-time understudy to Dan Carter, who started the 2011 final against France, will almost certainly have to undergo surgery after damaging the anterior cruciate ligament in his left knee during the first half of the 20-9 win in Christchurch.

While it is difficult to estimate exactly how long it will take for Cruden to recuperate, it is expected that he could be set to spend up to six months on the sidelines.

Such a layoff would obviously curtail his involvement in the current Super Rugby campaign and also surely put his international ambitions on hold, with New Zealand's first World Cup pool match coming against Argentina in September.

But Cruden insists he is not giving up totally on the idea of aiding coach Steve Hansen's star-studded squad on their quest to retain the title.

"I haven't completely ruled out making the World Cup," he said. "Looking at the last World Cup there were a few injuries and guys getting called in late so I guess, all going well with my rehab and my recovery ticks along nicely, then who knows what can happen.

"But at this stage I can't put all my energy into that - I just have to make sure I go up to Auckland on Wednesday, see the surgeon and make a plan from there and attack it step by step.

"To be honest it was hard to believe initially due to the fact the swelling around my knee hasn't blown up, it's a little bit sore but still feels reasonably strong.

"And just the nature of [how I did] the injury I guess - it wasn't a contact injury, I was just running, propping off to change direction and [it was like I] was struck down by a sniper."

Cruden started for the All Blacks in the 24-21 defeat of England in November 2014, two months after he was reprimanded and handed a two-match ban for missing a team flight to Argentina following a night out.

Carter returned to the international fold for the subsequent win over Scotland and is expected to remain first choice for his country until he leaves the Crusaders after the World Cup in order to represent Top 14 outfit Racing Metro.

The Hurricanes' Beauden Barrett and club teammate Colin Slade are likely to provide the main competition in Cruden's absence.