Tonga has lost the services of flyhalf Kurt Morath and center Nafi Tuitavake for the remainder of the Rugby World Cup after they were injured in their opening 35-3 Pool C defeat to England on Sunday.

Morath may require an operation on his throat after being caught by the boot of England's Manu Tuilagi while replacement center Tuitavake suffered a broken arm late in the game, Tonga assistant coach Pita Alatini said on Tuesday.

"Kurt is still in hospital in Sapporo and may need surgery," Alatini said. "He injured his larynx when Manu Tuilagi caught him with his boot in a tackle. It was totally accidental.

"Nafi broke his arm in the last play of the game."

Latiume Fosita had been named as a replacement for Morath, while Tonga has asked New Zealand's Tasman club for permission to call up Fetuli Paea ahead of its second game against Argentina in Osaka on Saturday.

"It is obviously desperately disappointing for Kurt and Nafi — they have worked so hard to be here — but it means there are opportunities for others now," said Alatini.

James Faiva, who is expected to start at flyhalf in place of Morath, said it was not the ideal circumstances to come onto the team but was determined to make the most of his chance.

"It's disappointing to lose Kurt the way we have, but we've got to keep moving forward as a team and I want to take the chance that has been given to me," he said.

"It's a great opportunity to show my talents."