New Zealand international Israel Dagg's World Cup hopes were in doubt after the Crusaders said on Tuesday the fullback would be sidelined for two to five months with a right thigh injury.

The 22-year-old Dagg, who can also play wing, had surgery on Monday after he ruptured a tendon in his right thigh in a Super 15 match in South Africa on May 7, the Crusaders said.

The World Cup starts on September 9, when host New Zealand opens the tournament against Tonga.

"It's definitely not the time to be injured but if we do everything right with the rehab I could be back playing by the end of July," Dagg told Hawke's Bay Today newspaper.

"I'll just have to take each step of the rehab as it comes, get the strength back in the quad again and keep positive."

The Crusaders said utility back Adam Whitelock and wing Sean Maitland would also be out for a similar period of time after they were hurt in the same Super Rugby game, a 20-14 win over the Stormers in Cape Town.

Whitelock also underwent surgery on Monday for a ruptured right pectoral muscle while Maitland will have surgery on his left foot on Wednesday.

Whitelock, Maitland and Dagg are all expected to miss the rest of the Super 15, which ends on July 9.

"A timeframe for a return for this trio depends on how the injuries respond to surgery and rehabilitation but they are likely to be out of the game for two to five months," the Crusaders said in a statement on their website.

"More definite timeframes will be known over the next few days."

The Crusaders added that scrumhalf Kahn Fotuali'i has a right knee ligament sprain, ruling him out for four to six weeks.

Fotuali'i was also injured in a nightmare first half for the seven-time Super champions in Cape Town. All four players returned to New Zealand last week.

The team said trio Andy Ellis (thumb), Brad Thorn (calf) and Sam Whitelock (ankle) were "progressing well" with their injuries, however. The three haven't played for over a month.

All Blacks skipper Richie McCaw and flyhalf Daniel Carter both returned for the injury-hit Crusaders in Saturday's defeat to the Cheetahs in Bloemfontein.

It was Carter's first game since March.

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